Healthy Eating: A guide to the new nutrition

Healthy Eating: A guide to the new nutrition

Dear Reader,

Healthy eating is easier than ever. That’s because we know so much more about what a healthy diet looks like than we ever have before. Choosing healthy foods based on good science remains the best known way to reduce your chances of developing heart disease and diabetes and to help ward off hypertension, osteoporosis, and some forms of cancer.

We’ve known for many years that certain foods promote good health — especially fruits, vegetables, some oils and fats, and whole grains. But now the nutritional science shows that there is not a single “healthy diet.” Instead, there are many patterns of eating around the world that sustain good health. They share these things in common: lots of fruits, vegetables, and whole grains; healthy fats from fish and plant sources; low amounts of salt; and few added sugars or solid fats. A healthy eating pattern also includes enough energy (calories) to fuel the body, but not so much as to cause weight gain.

In 2011, the U.S. Department of Agriculture (USDA) and the Department of Health and Human Services (HHS) jointly released the new Dietary Guidelines for Americans. These guidelines emphasize lowering calorie consumption and increasing physical activity to control the increasing prevalence of obesity, which contributes to heart disease, stroke, diabetes, and some cancers. The guidelines, described in this report, urge people to choose “nutrient-dense” foods, such as vegetables, and to avoid foods with empty calories, such as sugary sweets and refined white carbohydrates.

As a nutrition researcher and an ordinary citizen, I’m convinced that eating more whole foods — unprocessed foods with few ingredients listed on the label, if the product has a label at all — isn’t all that difficult. I know resourceful people with full-time jobs and families who, for example, make their own organic yogurt because they got tired of paying the high prices at the supermarket. It takes a little organizing to have the ingredients on hand and the right equipment, but actually putting it all together takes just minutes. That’s what this report will help you discover — that healthy eating is easier than you think. There are many ways to get away from factory-processed foods laden with fat, sugar, and salt.

This report provides the information you need to make the link between food and health. And it will guide you in making healthy choices whether at home or on the road. Bon appétit!


Teresa Fung, Sc.D., R.D., L.D.N.
Faculty Editor

Not long ago, a healthy diet could be summed up in two simple concepts. One: maintain a balanced diet of proteins, carbohydrates, and fats. Two: get the recommended amounts of vitamins and minerals. Cover these bases, and you’d have enough energy to power your body’s cells and enough nutrients to prevent deficiency diseases.

The basic notions of a healthy diet remain the same, but science has expanded on them. Everyone needs a mix of proteins, carbohydrates, and fats, plus enough vitamins and minerals, but we now know that some of the choices within these categories are better than others. There are good fats, which promote health, and bad fats, which increase your risk of illness. The same is true for carbohydrates and possibly for proteins. Regarding vitamins and minerals, the latest thinking goes beyond diseases caused by deficiency and now includes a knowledge of how these substances affect our health — from bone strength to birth defects, and from heart health to hypertension.

The form food comes in is also important. The healthiest foods are those that have undergone as little processing as possible, like those made from whole grains that come with their natural fiber and nutrients, rather than products made from white flour — which is stripped of these beneficial components — and then saturated with added salt, sugar, and fat. Although many processed foods are “fortified” with vitamins, the processing first removes their natural complement of nutrients and fiber. Those naturally occurring combinations are what the human body has evolved to thrive on over thousands of years. Foods reformulated in factories can’t begin to replicate the intricate nutrient combinations that nature itself has devised.

The sad fact is that processed foods such as chips, cookies, processed cheeses and meats, sodas, and energy drinks remain top sources of mostly empty calories for adults and children in the United States. In the typical American diet, 35% of our total daily calories come from foods high in saturated (solid) fat and added sugar, dubbed SoFAS by the USDA. That’s high. The USDA recommends that we get no more than 5% to 15% of our total daily calories from SoFAS, with the rest of our calories — at least 85% — from nutrient-dense, minimally processed foods, such as whole grains, fruits and vegetables, lean protein, and low-fat dairy products.

Beyond these basics of good nutrition — getting a variety of nutrients from whole foods and limiting salt, added sugar, and solid fats — it pays to become a more adventurous eater. You can, for example, move beyond foods made with wheat flour to other interesting grains like quinoa, buckwheat, barley, and even corn meal. If you’re not sure how to cook with them, the recipes on the packaging can help. Explore the produce department as well, or try something different when eating out. By expanding your palate, you’ll cast a wide net and consume a broader range of nutrients within your daily calorie budget that can help you put up a more powerful food fight against disease.

The food pyramid

It’s a clever idea: organize foods into a pyramid with the healthy foods at the wide bottom, to indicate these should form the foundation of the diet, and put unhealthy foods at the narrow top, to suggest you should eat only small amounts. The U.S. Department of Agriculture (USDA) developed its first food pyramid in 1992. After two decades of controversy the USDA eliminated it in 2011, switching to a dinner plate showing food proportions. It is now posted online at The concept of the food pyramid is still in use, however, as other experts, including those at Harvard, have come up with their own food pyramids.

Harvard’s Healthy Eating Pyramid

In the Harvard pyramid, the widest sections toward the bottom are for healthy things. The narrow top section is for foods that should be eaten only occasionally, if at all (see Figure 1). Harvard nutrition experts point out that we now know that most fats from plants and fish (unsaturated fats) are good for you, while those from animals (saturated fats) and in many processed foods (trans fats) are unhealthy. So sources of these different types of fat are listed separately on the pyramid according to their health benefits: healthy fats near the bottom, unhealthy fats at the narrow top.

Figure 1: The Healthy Eating Pyramid

The Healthy Eating Pyramid

The widest section at the bottom of this pyramid is for things that are most important. The top is for foods to be eaten only sparingly, if at all. Begin at the bottom with daily exercise and weight control. On the next step up are the healthiest foods: vegetables and fruits, healthy fats and oils, and whole grains. These should make up the bulk of your diet. Work your way up the pyramid until, at the top, you’ll find foods such as red meat, butter, and white starches that you should eat sparingly, if at all.

Adapted from Eat, Drink, and Be Healthy: The Harvard Medical School Guide to Healthy Eating, by Walter Willett, M.D.

Look at the Healthy Eating Pyramid and you’ll see that the largest part, the foundation, consists of daily exercise and weight control. Although good food choices will improve the health of overweight and obese people, to be truly healthy it’s important to maintain a normal weight and stay physically active. Physical activity and weight control help prevent several serious illnesses.

The next level includes foods with good fats and good carbohydrates. This level tells you that the most important foods to eat are fruits and vegetables, whole-grain foods (good carbohydrates), and plant oils (good fats).

Next come nuts, seeds, and legumes. The Healthy Eating Pyramid places nuts and legumes in their own category instead of lumping them with meat and fish to form one “protein” category. This reflects findings that some forms of protein are healthier than others (see “Update on protein”). Fish, poultry, and eggs are on the same level. Next are dairy products. At the very top are the foods you should eat least frequently: refined starches and sweets (bad carbohydrates) and red meat (particularly processed meat) and bad fats, including saturated fats from animal products like butter and trans fats found in many processed foods.

In doing the research for the Healthy Eating Pyramid, Harvard scientists examined the diets of more than 100,000 female nurses and male health professionals taking part in two long-term studies. They found that men whose diets most closely followed the Healthy Eating Pyramid lowered their overall risk of major diseases by 20% over eight to 12 years, compared with men whose diets scored lowest on the healthy eating recommendations. Women in the study who followed the Healthy Eating Pyramid lowered their overall risk by 11% compared with those who scored lowest. The big wins came with cardiovascular disease. The top nutritional scorers among both men and women cut their risk by one-third or more. Healthy diet and lifestyle lowered the risk of heart attacks even in people who were taking medications for high cholesterol or high blood pressure, showing that good nutrition has its own benefits independent of medications.

The Healthy Eating Pyramid isn’t set in stone. As nutrition researchers turn up more information over time, it will change to reflect important new evidence. And it’s not the only pyramid. If you’d like to check out some other healthy eating pyramids adapted to Mediterranean, Latin American, Asian, and vegetarian foods, go to the Web site for Oldways, the respected nutrition think tank, at

New Dietary Guidelines for Americans

Every five years, the government asks a committee to review the latest nutritional science and create recommendations for the public. The 2011 guidelines from U.S. Department of Agriculture and the Department of Human Services emphasize weight control. In previous years, the guidelines focused on nutrients: What proportion of fats, proteins, and carbohydrates is optimum for health? Or, what amounts of different vitamins and minerals do you need to avoid deficiencies and ward off disease?

The slogan for the 2011 guidelines is: “Calories in, calories out.” Put another way: Americans should strive to maintain a calorie balance, eating no more calories than they burn each day. If you are overweight, the goal is to eat fewer calories than you burn each day in order to reach a healthy weight. Calorie control and daily physical activity are the cornerstones of the guidelines.

Why the emphasis on weight control? The Dietary Guidelines report explains it this way: “Poor diet and physical inactivity are the most important factors contributing to an epidemic of overweight and obesity affecting men, women, and children in all segments of our society. Even in the absence of overweight, poor diet and physical inactivity are associated with major causes of morbidity and mortality in the United States.” With this in mind, the Dietary Guidelines include these recommendations for foods to cut back and foods to increase:

Foods to reduce

  • Reduce daily sodium intake to less than 2,300 milligrams (mg) and further reduce intake to 1,500 mg among persons who are 51 and older and those of any age who are African American or have hypertension, diabetes, or chronic kidney disease.

  • Consume less than 10% of calories from saturated fatty acids by replacing them with monounsaturated and polyunsaturated fatty acids.

  • Consume less than 300 mg per day of dietary cholesterol.

  • Keep trans fatty acid consumption as low as possible.

  • Reduce the intake of calories from solid fats and added sugars.

  • Limit the consumption of foods that contain refined grains, especially those with solid fats, added sugars, and sodium.

  • If alcohol is consumed, it should be consumed in moderation — up to one drink per day for women and two drinks per day for men — and only by adults of legal drinking age.

Foods and nutrients to increase

  • Strive to increase your intake of these foods while staying within your calorie goals.

  • Eat a variety of fruits and vegetables, especially dark green, red, and orange vegetables, fruits, and beans and peas.

  • Consume at least half of all grains as whole grains. Increase whole-grain intake by replacing refined grains with whole grains.

  • Increase intake of fat-free or low-fat milk and milk products, such as milk, yogurt, cheese, or fortified soy beverages.

  • Choose a variety of protein foods, which include seafood, lean meat and poultry, eggs, beans and peas, soy products, and unsalted nuts and seeds.

  • Choose seafood in place of some meat and poultry.

  • Replace protein foods that are high in solid fats with proteins that are low in solid fats and calories.

  • Use healthy vegetable oils to replace solid fats where possible.

  • Choose foods that provide more potassium, dietary fiber, calcium, and vitamin D, which are nutrients of concern in American diets. These foods include vegetables, fruits, whole grains, and milk and milk products.

How do you know the difference between a good fat and a bad fat? The same question applies to carbohydrates and proteins. These foods, known as macronutrients, are the basic categories of nutrients that humans need. They provide the body with energy, and they enable the body to carry out many normal biological functions. A healthy diet consists of a mix of foods from each of these three macronutrient categories, although not in equal amounts. The latest science tells us that instead of focusing on individual nutrients, it’s best to think about your overall dietary pattern. Try for a mix of whole foods from nature, not factory-made foods, with a variety of sources of fats, carbs, and proteins.

There is no one healthy diet, but many, from around the world. One example of a healthy mix of fats, carbohydrates, and proteins is the Mediterranean diet; another is known as the DASH (Dietary Approaches to Stop Hypertension) diet (see “Eating plans for good health”). It and variations known as DASH-style diets are high in fruits and vegetables and healthy plant oils.

A panel of U.S. and Canadian scientists backed by the National Academy of Sciences’ Institute of Medicine has set dietary reference intakes (DRIs) for macronutrients based on research on diet and health (see “How much of each?”). The DRIs set forth the range of macronutrients in a diet balanced to maintain a healthy weight and to prevent serious conditions such as heart disease, cancer, hypertension, and diabetes. The DRIs also provide guidelines for fiber (a form of indigestible carbohydrate that serves several functions in the body) and vitamins and minerals.

How much of each?

Following are the dietary reference intakes (DRIs) for fats, carbohydrates, and proteins — the amounts needed daily to meet nutritional needs for adults while minimizing risk for disease. But keep in mind that more important than strictly adhering to these percentages is making sure to choose healthy sources for fats, carbohydrates, and proteins, as described in this report.

Fats: 20% to 35% of daily calories (reduce saturated and trans fats as much as possible while consuming a nutritionally adequate diet).

Protein: 10% to 35% of daily calories.

Carbohydrates: 45% to 65% of daily calories (reduce consumption of added sugar).

Fiber (indigestible carbohydrate): 14 grams per every 1,000 calories. That’s about 21 to 38 grams a day, based on age and sex, as follows:

  • men ages 50 and younger: 38 grams/day

  • women ages 50 and younger: 25 grams/day

  • men over age 50: 30 grams/day

  • women over age 50: 21 grams/day.

Dietary Reference Intakes: The Essential Guide to Nutrient Requirements, Institute of Medicine (National Academy of Sciences).

All about fat

Fat now makes up about one-third of the average American’s diet. At one time, experts encouraged people to eat less fat. These days, experts are more concerned about the type of fat you eat, especially for heart health, thanks in part to decades of studies at Harvard Medical School and the Harvard School of Public Health. This change was further supported in 2006 when the Women’s Health Initiative, a national study of about 49,000 women, showed that a low-fat diet didn’t significantly reduce the women’s risk of heart disease, breast cancer, or colon cancer. As it turns out, it’s the type of fat you eat, not the total amount, that counts.

The body needs fat. It’s a major energy source and also helps you absorb certain vitamins and nutrients. Certain fats from plant sources and fish turn out to be the most beneficial. These unsaturated fats — which come mainly in the form of vegetable oils, nuts, and whole grains — are good for you. There are two types of unsaturated fat: polyunsaturated fat and monounsaturated fat. These good fats can help lower LDL (bad) cholesterol, prevent abnormal heart rhythms, and prevent heart disease. (For more information on fats and specific illnesses, see “The food-health connection”.)

Only some fats are bad for you: trans fats (found in some manufactured foods and margarines) and some saturated fats (found mainly in meat and whole-fat dairy foods). Bad fats boost your chances of developing heart disease by increasing blood levels of two of its main risk factors, LDL cholesterol and triglycerides. Trans fats also lower levels of protective HDL, the “good” cholesterol.

The DRI for fat gives considerable leeway: 20% to 35% of your daily calories can come from fat. This means you can get up to 35% of your calories from fat and still have a diet that’s good for your heart, helps reduce your risk of hypertension, and lets you maintain your weight or even lose weight. Even more may be fine, so long as it’s mostly healthy fats from fish and vegetables (see “Eating plans for good health”).

Although research results are conflicting, it’s best to limit red meat, particularly processed meat, and full-fat dairy products like butter, cheese, and ice cream. Try to choose non-fat or low-fat dairy products and lean cuts of meat, poultry, fish, soy, and beans. Processed and cured meats are particularly linked to an increased risk of cardiovascular disease. For trans fats, there is no safe level, and the guidelines recommend eating as little as possible.

What’s the difference between a good fat and a bad fat? All fats have a similar chemical structure: a chain of carbon atoms bonded to hydrogen atoms. What differs is the length and shape of their carbon chains and the number of hydrogen atoms connected to the carbon atoms. Seemingly slight differences in structure translate into crucial differences in the body.

Bad fat

The two forms of unhealthy fat, trans fats and saturated fats, share a physical trait: they’re solid at room temperature. Think of butter, margarine, shortening, or the marbled fat in a steak. But bad fats abound in some liquids, too, including whole milk, cream, and palm and coconut oils. These fats drive up your total cholesterol, tipping the balance toward LDL cholesterol, the destructive type that prompts blockages to form in the coronary arteries, the hallmark of heart disease. The expert panel of the National Cholesterol Education Program recommends cutting back on saturated and trans fats as a means of preventing and controlling heart disease.

Saturated fat. The word “saturated” here refers to the number of hydrogen atoms in this type of fat. In saturated fat, the chain of carbon atoms holds as many hydrogen atoms as possible, making it literally saturated with hydrogen atoms. Each carbon atom in the chain is connected to the next by a single bond, leaving the maximum number of bonding points available to hold hydrogen. By contrast, in unsaturated fats, the carbon atoms have fewer than the maximum number of hydrogens.

Saturated fat, which is concentrated in full-fat dairy products and meat, has received some positive publicity in the media lately. Maybe you’ve seen reports that it doesn’t cause heart disease after all. Unfortunately, many media stories oversimplified the conclusions of the scientists who conducted a 21-study meta-analysis published in The American Journal of Clinical Nutrition in 2010.

The study really said that there was not enough evidence to conclude that saturated fat increases the risk of heart disease, but that replacing saturated fat with polyunsaturated fat may indeed reduce risk of heart disease.

Two other major studies in the same academic journal narrowed the prescription slightly, concluding that replacing saturated fat with polyunsaturated fats like vegetable oils or high-fiber carbohydrates is the best bet for reducing the risk of heart disease. All told, if you are trying to reduce saturated fat, your best choice is to replace it with polyunsaturated oils, like corn oil.

In regards to cholesterol, a diet high in saturated fats boosts total cholesterol by elevating harmful LDL. Like all dietary fat, saturated fat also raises the protective HDL. But eating unsaturated fat is a better choice because it lowers the bad cholesterol and raises the good.

Trans fats (partially hydrogenated oils). Trans fats are rapidly fading from the scene, thanks to the government requirement that they be listed on food labels. Trans fats were created in the laboratory to provide cheap alternatives to butter. Food chemists learned how to solidify vegetable oil by heating it in the presence of hydrogen and a heavy-metal catalyst such as palladium. The process, called hydrogenation, gives the carbon atoms more hydrogen atoms to hold, making polyunsaturated fat (a good fat) more like saturated fat in structure. That’s how solid vegetable fats such as shortening and margarine came into being. On food label ingredient lists, this manufactured substance is typically listed as “partially hydrogenated oil.”

Trans fats are even worse for you than saturated fats. Not only do they increase your LDL cholesterol, but they also reduce your beneficial HDL cholesterol. The Institute of Medicine expert panel stated that trans fats have no known health benefits and that there is no safe level of consumption.

Since 2006, the FDA has required trans fat content to be listed as a separate line item on food labels. As a result, the food industry has reduced trans fats in many foods, and some local governments have banned trans fats in restaurant foods. Happily, these mainly man-made fats, which used to be in everything from commercial cookies to fast-food fries, are now much less prevalent. Harvard researchers and the Center for Science in the Public Interest, a consumer advocacy group, analyzed 83 reformulated supermarket and restaurant foods and found that nearly all of them were free or mostly free of trans fat, and that saturated fat hadn’t replaced it, yielding products and menu items with a healthier balance of fats.

Be aware that although many labels now state “0 trans fat,” manufacturers can still sneak them in. According to the labeling law, if a product has no more than half a gram of trans fat per serving, the label can list it as having 0 grams of trans fat. By making the serving size very small (two small cookies, for example), the manufacturer may thus be able to label a product as having 0 grams trans fat per serving. But if you eat six cookies, you may have consumed nearly 3 grams of trans fat. Check the label for hydrogenated oils and be wary of foods with small serving sizes. And keep in mind that just because a cookie is listed as having no trans fat, it’s still a cookie, which can be loaded with saturated fat, sugar, and empty calories.

Good fat

Good fats come mainly from vegetable, nut, and fish products. They differ from bad fats by having fewer hydrogen atoms bonded to their carbon chains. They are liquid, not solid, at room temperature. There are two broad categories of beneficial fats: polyunsaturated and monounsaturated.

Polyunsaturated fats. When you pour liquid cooking oil into a pan, there’s a good chance you’re using polyunsaturated fat. Corn oil, sunflower oil, and safflower oil are common examples. (The exceptions are sunflower and safflower oils labeled “high-oleic,” which come from crops intentionally bred to produce mostly monounsaturated fats.) Polyunsaturated fats are essential fats. That means they’re required for normal body functions, but your body can’t manufacture them and so you must get them from food. Polyunsaturated fats help build cell membranes, the exterior casing of each cell, and the sheaths surrounding nerves. They’re vital to blood clotting, muscle movement, and inflammation. They reduce LDL more than other types of fats, improving your cholesterol profile. Even better, they also lower triglycerides.

A polyunsaturated fat has two or more double bonds in its carbon chain. There are two types of polyunsaturated fats: omega-3 (n-3) fatty acids and omega-6 (n-6) fatty acids. (The numbers refer to the distance between the end of a carbon chain and the first double bond.) Both types offer health benefits.

Research has shown that omega-3s in dietary fish and fish oil supplements help prevent and even treat heart disease and stroke. The reasons are several: these fats help reduce blood pressure, raise HDL, lower triglycerides, and — perhaps most importantly — prevent lethal heart-rhythm disorders. Evidence also suggests they may help reduce the need for corticosteroid medications in people with rheumatoid arthritis. Unfortunately, most of the other studies linking omega-3s to a wide range of other health improvements, including reducing risk of dementia, are inconclusive, and some of them have major flaws, according to a systematic review of the evidence by the Agency for Healthcare Research and Quality.

Omega-3s come mainly from fish, but you can also find them in flaxseeds, walnuts, canola oil, and unhydrogenated soybean oil. Fatty fish such as salmon, mackerel, and sardines are especially good sources of omega-3s. The DRI for alpha-linolenic acid, the omega-3 in vegetable oils, is 1.6 grams per day for men and 1.1 for women.

Omega-6 fatty acids are even more protective against heart disease. High levels of linoleic acid, an omega-6, are in such vegetable oils as safflower, soybean, sunflower, walnut, and corn oils. (Be aware, however, that high-oleic safflower and sunflower oils, often used in chips, have much lower omega-3 and omega-6 content.) The DRI for linoleic acid is 17 grams per day for men ages 19 to 50 and 12 grams for women in this age group. For adults ages 51 to 70, the DRI is 14 grams for men and 11 grams for women.

Monounsaturated fats. When you dip your bread in olive oil at an Italian restaurant, you’re getting mostly monounsaturated fat. Unlike a polyunsaturated fat, which has two or more double bonds of carbon atoms, a monounsaturated fat has just one. The result is that it has more hydrogen atoms than a polyunsaturated fat, but fewer than a saturated fat. Although there’s no DRI for monounsaturated fats, the Institute of Medicine recommends using them as much as possible along with polyunsaturated fats to replace saturated and trans fats. Good sources of monounsaturated fats are olive oil, peanut oil, canola oil, avocados, and most nuts, as well as high-oleic safflower and sunflower oils.

The discovery that monounsaturated fat could be healthful came from the Seven Countries Study during the 1960s. This study revealed that people in Greece and other parts of the Mediterranean region enjoyed both a low rate of heart disease and a high-fat diet. The fat in their diet, however, was not the animal fat common in other countries with higher rates of heart disease: it was olive oil, which has mainly monounsaturated fat. This finding produced a surge of interest in olive oil and the “Mediterranean diet,” a style of eating regarded as a healthful choice today.

Building your plate

At mealtime, simplify the process of healthy eating by dividing your plate in half. Fill one half with vegetables. Divide the other half into two quarters, filling one quarter with lean protein such as fish or skinless chicken. Fill the remaining quarter with whole grains such as brown rice, whole-wheat pasta, barley, or quinoa.

  • Keep portion sizes moderate to avoid weight gain.

  • Choose beverages with little or no sugar.

  • Then, after you eat, go out for a walk.

What about carbohydrates?

Carbohydrates encompass a broad range of foods, including table sugar, fruits and vegetables, and grains such as rice and wheat. The DRI for carbohydrates is 45% to 65% of your daily calories. But, as the Healthy Eating Pyramid shows, most of these carbohydrates should come from whole-grain foods, vegetables, and fruits. If most of the carbohydrates you eat are bad carbohydrates (white bread, white potatoes, white rice, and other refined starches or sugars found at the top of the Healthy Eating Pyramid), you could end up gaining weight and putting yourself at risk for disease.

The list of bad carbohydrates may come as a surprise. Why point the finger at potatoes? They’re vegetables, after all. Why are they in the same category as sweets? To answer these questions, you have to consider the glycemic index of a food.

The glycemic index reflects the spike in blood sugar caused by eating a certain amount of a particular food compared with that of white bread or pure sugar. In general, healthy carbohydrate foods have a lower glycemic index than unhealthy ones. White pasta has a higher glycemic index than whole-wheat pasta because it raises blood sugar more than the same amount of whole-wheat pasta.

You may also have heard the term glycemic load. This is often a more useful term because it describes both the amount of carbohydrate in a serving of food and how fast that amount will raise your blood sugar level. The glycemic load is simply the food’s glycemic index times the amount of carbohydrate in a serving. For example, a big slice of white bread will spike the blood sugar more than a little slice of the same white bread. The glycemic index is the same for both pieces, but the glycemic load is higher for the large piece. For menu-planning purposes, the glycemic load is more meaningful than the glycemic index because it’s based on the portion size of a particular food eaten.

Foods with a high glycemic index are digested more quickly than foods with a low glycemic index (see Table 1). Rapidly digested foods can be dangerous because they flood your bloodstream with sugar all at once. Sudden, high spikes of blood sugar trigger a gush of insulin to clear the sugar from your blood. The problem is that this quick surge of insulin can leave your blood sugar too low after just a few hours. When your blood sugar is too low, you feel hungry; if it’s low soon after a meal, you’re apt to overeat and possibly gain weight.

Another problem with a steady diet of high-glycemic meals is that over many years, your body’s system of responding to insulin could become impaired. This is called insulin resistance. When your cells are less responsive to insulin, the resulting overload of sugar in your bloodstream forces the pancreas to produce more insulin in an effort to move the sugar (glucose) from the blood into the cells. This itself will further reduce the response of muscles to insulin to take up sugar from the blood. As this situation worsens, blood sugar rises chronically to an abnormal level defined as type 2 diabetes. If the pancreas is forced into overdrive for a sustained period, it may wear down and eventually lose some of its ability to produce insulin, leading to insulin deficiency and worsening of type 2 diabetes. Insulin resistance can also cause other problems, including heart disease and perhaps some cancers.

Table 1: Choosing foods with a low glycemic index

Low glycemic index
(best choice)

Moderate glycemic index

High glycemic index


asparagus, avocado, broccoli, carrots, celery, chard, lettuce, mushrooms, okra, onion, peppers, spinach, tomatoes, zucchini

beets, butternut squash, green peas, parsnips, plantain, pumpkin, sweet potato

corn, French fries, potato, potato chips


apples, berries, cantaloupe, cherries, grapefruit, grapes, kiwi, lemon, nectarines, oranges, peaches, pears, plums

applesauce, banana, dried fruit, mango, papaya, pineapple, watermelon

fruit juices and drinks


almonds, cashews, peanut butter (no added sugar), peanuts, pecans, pistachios, walnuts

peanut butter (with sugar)


steel-cut oats

amaranth, barley, bread (whole-grain, minimally processed), breakfast cereal (high-fiber), brown rice (varies by type), buckwheat (kasha), bulgur, millet, pasta (not canned), quinoa, wheat berries, wild rice

Products made with highly processed white flour such as bagels, buns, corn bread, English muffins, pita, breakfast cereals, couscous, crackers, pancakes, pasta (canned), popcorn, pretzels, rice cakes, stuffing, taco shells, tortillas, white rice


cheese, milk, yogurt (no added sugar)

Source: Ending the Food Fight, by David Ludwig with Suzanne Rostler (Houghton Mifflin, 2008). See to look up more foods.

Good carbs, bad carbs

The high-carbohydrate foods that are good for you can help protect against health problems in part because they have a relatively low glycemic load. They’re digested slowly, which means they cause a gradual rise in blood sugar. How can you tell the difference? You can gauge whether a carbohydrate is good or bad based on these characteristics:

How heavily processed is the food? Some scientists think that the glycemic load of the average American diet has increased because we’re eating greater amounts of prepared foods that contain heavily processed carbohydrates. One factor in a grain product’s glycemic load is its degree of refinement. In general, the smaller the pieces, the faster they’re digested. This is one reason finely ground white wheat flour is digested faster than coarsely ground (sometimes called “stone-ground”) wheat flour. It’s the same with steel-cut oats compared with instant or “quick” oatmeal.

Processing also removes the fibrous casing from grains. This casing is good for you because it slows digestion and contains a host of nutrients that may lower the risk of some diseases. Studies show that whole-grain foods such as brown rice and barley, which have their fibrous casing intact, are healthier than the more heavily processed refined grains. In results from two large ongoing studies, the Nurses’ Health Study and the Health Professionals Follow-up Study, people who ate the most whole grains (four slices of whole-wheat bread daily) were less likely than other people to develop type 2 diabetes, heart disease, and several types of cancer, including cancer of the mouth, stomach, colon, gallbladder, and ovary.

Is it really whole grain? Not all foods in the grocery store that claim to be “whole grain” really are. “Whole-wheat” bread may include a lot of refined white flour. Look for labels that say “100% whole wheat” (or oats or rye or another grain). Read the ingredients list to make sure that the first ingredient is a whole grain.

Some whole-grain foods can be easily spotted by their color. Brown rice is a whole grain (it’s brown because its casing is intact), but white rice isn’t. But color isn’t always a good indicator because some whole-grain products don’t look the part. As you’ll notice in restaurants advertising “whole-wheat pizza crust” and on grocery store shelves, some whole-grain breads and other items are now white. Whole-wheat white bread may sound like an oxymoron, but it’s the real deal. This color trend is part of the increasingly creative effort that food companies are making to introduce whole-grain products into the grocery carts of the white-bread-only consumer. To make whole-grain bread white, manufacturers use an albino variety of whole-wheat flour that’s lower in gluten and softer in texture. Because the flour isn’t refined, it’s technically a whole grain. However, it’s so new to the market that its glycemic index is still unknown.

How much fiber is in the food? Fiber is the indigestible part of grains, vegetables, and fruits. Its delays the time it takes for the food to be digested. Whole-grain foods have more fiber than refined foods (see “Fiber: The workhorse”).

How much fat is in a meal or snack? You’ll reduce the spike in blood sugar from carbohydrates by combining the food with protein or fats. Because fats take longer to digest than carbohydrates, the more fat a meal or snack has, the more slowly it will be digested and, possibly, the less detrimental an effect it will have on your blood sugar. Just make sure that the fat or protein is a healthful one. A handful of cashews or other nuts is a better snack than a cookie made with butter or trans fats.

Figure 2: How sweet is it?

How sweet is it?

Calories and teaspoons of sugar in 12 ounces of each beverage. For more information, see The Nutrition Source,

Fiber: The workhorse

Fiber is a form of indigestible carbohydrate found mainly in plant foods. Over the years, fiber has been hailed as a potential weapon against cancer, high cholesterol, and heart disease. Fiber’s vaunted health benefits were diminished slightly by findings that it doesn’t prevent colon cancer or colon polyps (precursors of colon cancer). Studies continue to be published, however, presenting a mixed picture. (See “Controlling colorectal cancer.”) What is known is that fiber slightly reduces LDL cholesterol, improves insulin resistance, and is linked to a lower rate of heart disease, type 2 diabetes, and obesity. There’s also some evidence that fiber might reduce the risk for duodenal ulcers, breast cancer, and ovarian cancer. It’s considered one of the most important health attributes of foods.

Fiber slows digestion and therefore lowers a food’s glycemic load, which likely helps to prevent diabetes. By increasing the bulk of foods and creating a feeling of fullness, fiber may also help you avoid overeating and becoming overweight.

Studies such as the Nurses’ Health Study and the Health Professionals Follow-up Study have found that people with the lowest rates of heart disease and heart attack have the highest intakes of fiber. These studies formed the basis for the DRIs for fiber.

The DRI for fiber is 38 grams for men up to age 50 and 25 grams for women in this age group. For pregnant women, the DRI is 28 grams, and for breast-feeding women, 29 grams. DRIs are lower for people over age 50: 30 grams for men, 21 grams for women. That’s because older people tend to eat less food. On average, Americans eat only about 15 grams of fiber a day.

You can probably identify some high-fiber foods, such as bran cereals and whole-grain bread (see Table 2). But not all foods billed as “high-fiber” really have much; read the labels on packaged foods to see the number of grams of fiber they contain. You can be sure of getting fiber if you eat fruits, vegetables, and whole-grain foods such as whole-wheat bread, brown rice, bran, or oats each day.

Table 2: Good sources of fiber


Fiber content in grams*

Split peas, cooked, 1 cup


Red kidney beans, boiled, 1 cup


Raspberries, raw, 1 cup


Whole-wheat spaghetti, 1 cup


Oat-bran muffin, medium


Pear, medium with skin


Broccoli, boiled, 1 cup


Apple, medium with skin


Oatmeal, quick, regular, or instant, cooked, 1 cup


Green beans, cooked, 1 cup


Brown rice, cooked, 1 cup


Popcorn, air-popped, 2 cups


Whole-wheat bread, one slice


*Fiber content can vary among brands and varieties.

Source: USDA National Nutrient Database for Standard Reference, 2007.

Fiber can also take the form of over-the-counter supplements, which come as pills or powders. These provide some of the same benefits as fiber in foods. But foods naturally high in fiber have the edge, as they help you feel full on fewer calories, which can help keep your weight in check. Fiber pills don’t provide that feeling of fullness. If you decide to take fiber supplements, be sure to take them with plenty of water to maximize their benefits.

Here are some ways to make sure that your diet meets the DRI for fiber.

Eat whole-grain cereal for breakfast. Oats are an excellent choice, particularly steel-cut oats, which have the most fiber and the lowest glycemic index. If you prefer cold cereal, choose products that contain bran or list whole wheat, oats, barley, or another whole grain first on the list of ingredients.

Choose whole-grain breads. As with cereals, true whole-grain breads list a whole grain first in the ingredients. Whole-grain sliced bread, pita bread, and rolls are equally good.

Skip the French fries and baked potatoes. Instead of white potatoes, eat sweet potatoes (sometimes called yams). Instead of white rice, eat brown rice or another intact grain as a side dish. Good choices are buckwheat (kasha), bulgur, millet, quinoa, and barley.

Try whole-wheat pizza and pasta. Prepared pizzas made with whole-wheat crust are joining whole-wheat pastas on supermarket shelves. Many are now made with a variety of flour or flour blends that look white and cook up lighter, but are actually whole wheat. Traditional brown whole-wheat pasta is a great choice, too, but if it doesn’t appeal to you, another option is to mix whole-wheat pasta with regular white pasta.

Cook with whole-wheat flour. You can make breads, muffins, and other home-baked goods healthier if you mix whole-wheat flour with white flour. Many stores sell a multigrain pancake mix you can use for pancakes or waffles. Or instead of traditional whole-wheat flour, buy white whole-wheat flour, which has a finer grain than traditional whole-wheat flour and looks white. It can be substituted for regular white flour in many recipes. If you use traditional whole-wheat flour, a straight substitution won’t work for every recipe, because whole-wheat flour is heavier than white flour. Try starting with a ratio of one part whole wheat to three parts white to see if you like the results. If you think the dish could stand a heavier, grainier texture, try increasing the share of whole-wheat flour. You may need to increase the amount of liquid at the same time.

The soy story

For a long time, soybean-based beverages and foods like soy milk and tofu were the royalty of health foods: vegetarian, rich in protein, maybe responsible for the lower rates of heart disease and cancer in China and Japan. That many Americans had to acquire a taste for soy made it seem even healthier in that eat-your-peas way.

Early research suggested that soy protein was “heart healthy” because it could lower LDL (bad) cholesterol levels, but subsequent studies and judgments have dampened that enthusiasm. The results for soy protein have been so unimpressive that the American Heart Association has asked the FDA to rescind its 1999 decision that allowed food companies to label soy products as having heart disease–reducing benefits.

There have also been worries that the estrogen-like chemicals in soy, called isoflavones (pronounced eye-so-FLAY-vones), might promote the growth of estrogen-sensitive cells and therefore increase the chance of breast cancer recurrence. Study results reported in 2009 in TheJournal of the American Medical Association (JAMA) allay that concern to some extent.

But how soy and its isoflavones behave in the body is complicated. In some parts — such as bone — isoflavones appear to mimic estrogen, occupying the same receptors and therefore having a similar, if weaker, effect. If soy’s isoflavones impersonate estrogen in bone, that’s a good thing, because estrogen protects against bone loss by inhibiting osteoclasts, cells that break down bone, and stimulating osteoblasts, cells that build it up. But in other parts of the body — the breast, for example — the estrogen-like effects of isoflavones might mean extra cell growth and division and an increase in the risk of a cancer developing.

The bottom line: soy has emerged from the thousands of studies a bit humbled. It’s an excellent source of protein, which is especially important to vegetarians and vegans who need plant-based protein. And, yes, there are many nutritionally valid reasons to steer toward a vegetarian diet. But current science suggests that although soy is a relatively healthy food choice, it is not a particularly important player in preventing disease.

Update on protein

How much protein do you need? That question has been the subject of debate for decades, and the range set by the DRIs is wide: 10% to 35% of your daily calories can come from protein. For most men and women, protein provides about 15% of their total daily calories, which is right in the ballpark. You’re better off, however, if you choose proteins from foods like fish, skinless chicken, beans, soy, nuts, and whole grains.

Protein is everywhere in your body. It’s in your muscle, organs, bone, skin, and every other body part or tissue. It has many functions, including building the enzymes that trigger many of the important chemical reactions. About 20 amino acids supply the raw material for the body’s proteins. Following genetic instructions, the body strings together these amino acids into chains to make the specific proteins it needs. If those amino acids aren’t available, your body scavenges protein from its tissues to get them.

Ideally, the body needs a daily supply of amino acids to make new proteins. This supply comes from the protein in food. A lack of protein in the diet can slow growth, reduce muscle mass, lower immunity, weaken the heart and respiratory system, and even cause death. Most people in the United States and other industrialized countries eat plenty of protein, though.

So how much protein should you eat? In establishing the upper limit of 35%, the Institute of Medicine cautioned against exceeding that amount because some studies show that high-protein diets may promote some diseases, such as osteoporosis. When you eat a lot of protein, especially animal protein, your body draws some calcium out of your bones to help metabolize it. But so long as you eat sufficient calcium your bones will not suffer.

Indeed, studies suggest that eating plenty of protein may reduce heart disease. In the Nurses’ Health Study, the women who ate the most protein — which in this analysis was about 25% of their daily calories — were 25% less likely to have had a heart attack or to have died of heart disease than the women who ate the least protein, 15% of their calories. This finding agrees with the 2005 results of the OmniHeart Study, which showed that increasing dietary protein from 15% to 25% lowered blood pressure, LDL cholesterol, triglycerides, and estimated risk of heart disease.

What kind of protein is best? When it comes to foods that prevent or promote disease, experts know less about dietary protein than they do about fats and carbohydrates. Still, large, ongoing studies have revealed some connections between the type of protein people eat and their risk for particular illnesses.

Of particular interest is whether protein from vegetable sources — such as lentils, beans, and nuts — is healthier than protein from meat, which is a major source of protein in the Western diet. Evidence suggests that substituting vegetable protein for animal protein may lower the risk for heart disease. In an analysis of Nurses’ Health Study data, a low-carbohydrate diet moderately lowered the risk of coronary artery disease, but only when the fat and protein came from vegetable sources, according to an article published in 2006 in The New England Journal of Medicine.

Again in 2010, when researchers from the Harvard School of Public Health analyzed more Nurses’ Health Study data, they found that eating one serving per day of nuts, fish, or chicken in place of red meat lowered the risk of heart disease by 30%. The study concluded that shifting to protein-rich foods other than red meat could play an important role in lowering the risk of heart disease.

Processed meats may be the real culprit. A study published in the journal Circulation in 2010 analyzed data from 20 studies of diet and health from 1.2 million initially healthy participants, about 3 % of whom went on to develop heart disease, diabetes, or stroke. Results showed that red meat wasn’t associated with heart disease or type 2 diabetes as long as it was unprocessed. Processed meat, such as bacon and hot dogs, boosted the risk of heart disease by 42% and type 2 diabetes by 19%.

Still, eating red meat (beef, pork, and lamb) or processed meats increases the risk of colon cancer. One possible explanation is that cooking meat at high temperatures, such as on the grill, produces cancer-causing substances called heterocyclic amines, among others. Or the culprit might be the nitrates used in processing the meat rather than meat itself or the cooking method. In any event, you’re probably much better off with natural peanut butter or hummus on your sandwich rather than ham, salami, or baloney.

Over all, there are plenty of reasons to favor plant protein — such as protein-rich vegetables and beans — over red and processed meats. These plant proteins come in healthier packages than meat protein (see Table 3). And not only are these plant-based foods a good source of healthy polyunsaturated and monounsaturated fat, they also provide fiber, which has several health benefits (see “Fiber: The workhorse”) as well as vitamins and minerals.

Table 3: Good sources of protein

These foods contain lots of protein and little or no unhealthy fat.


Percentage of calories from protein





Skim milk


Low-fat yogurt




Kidney beans


Lentil soup




Source: U.S. Department of Agriculture

The best animal sources of protein are fish and poultry, because they’re relatively low in saturated fat. Fish, especially fatty fish such as salmon, also provide omega-3 fats, which help prevent heart attacks, sudden cardiac death, and certain types of stroke by decreasing blood clots, erratic heart rhythm, inflammation, and triglycerides, while raising beneficial HDL cholesterol. Fish and chicken are good options but should still be considered accessories to your diet, filling just one quarter of your plate, while filling the remaining three quarters with whole grains, vegetables, beans, and other produce. If you eat red meat, make it only an occasional part of your diet; opt for small portions, choose lean cuts, and — to minimize your colon cancer risk — avoid charring your meat on the grill. Also, avoid processed meats, such as ham, bacon, pastrami, salami, sausage, bratwurst, hot dogs, and pepperoni, since these foods raise the risk of colon cancer, heart disease, and diabetes.

What to do about mercury in fish

Fish is an excellent source of protein, and its healthy oils protect against cardiovascular disease. However, nearly all fish and shellfish contain traces of mercury, a toxic metal, and some seafood contains other pollutants known as POPs. As small fish are eaten by larger fish up the food chain, concentrations of mercury and POPs increase, so that large, predatory deep-ocean fish tend to contain the highest levels. That makes it best to avoid eating these large fish, such as shark, swordfish, tilefish, and king mackerel.

Because a diet rich in seafood protects the heart and benefits neurological development, fish remains an important component of a healthy diet.

Recommendation: Most adults can safely eat about 12 ounces (two 6-ounce servings) of a variety of cooked seafood a week as long as they avoid the large predatory ocean fish mentioned above and pay attention to local seafood advisories.

For women who are pregnant or may become pregnant, nursing mothers, and children ages 12 and younger, caution is needed to avoid potential harm to a fetus’s or a young child’s developing nervous system. The same amount, 12 ounces, is considered safe with these additional guidelines:

  • Eat up to 12 ounces (two average meals) a week of a variety of fish and shellfish that are lower in mercury. Five of the most commonly eaten fish that are low in mercury are shrimp, canned light tuna, salmon, pollock, and catfish.

  • Another commonly eaten fish, albacore (“white”) tuna, has more mercury than canned light tuna. So, when choosing your fish and shellfish, eat no more than 6 ounces (one average meal) of albacore tuna per week.

  • Check local advisories about the safety of fish caught by family and friends in your local lakes, rivers, and coastal areas. If no advice is available, eat up to 6 ounces (one average meal) per week of fish from local waters, but don’t consume any other fish during that week.

  • Follow these same recommendations when feeding fish and shellfish to your young child, but serve smaller portions.

Every day your body produces skin, muscle, and bone. It churns out red blood that carries nutrients and oxygen to remote outposts, and it sends nerve signals skipping along thousands of miles of brain and body pathways. It also formulates chemical messengers that shuttle from one organ to another, issuing the instructions that help sustain your life. To do all that, your body requires at least 30 vitamins, minerals, and dietary components that your body can’t manufacture in sufficient amounts. So you need to get them from foods or other sources.

These essential vitamins and minerals are often called micronutrients because unlike the case with macronutrients — protein, fat, and carbohydrates — your body needs only tiny amounts of micronutrients. Yet failing to get these small quantities virtually guarantees disease. Old-time sailors learned that living for months without fresh fruits or vegetables — the main sources of vitamin C — caused the bleeding gums and listlessness of scurvy. In some developing countries, people still become blind from vitamin A deficiency. And even in the United States, some children develop the soft, deformed bones of rickets because they don’t get enough vitamin D (see Table 4).

Table 4: Vitamins and minerals with extra health benefits

Vitamin or mineral


Recommended amount by age

Upper limit (UL) per day

Good food sources

Vitamin B6 (pyridoxal, pyridoxine, pyridoxamine)

Helps lower homocysteine levels. Not clear whether it lowers heart disease risk. Helps make red blood cells. Influences cognitive abilities and immune function.

Ages 19–50:

Men: 1.3 mg
Women: 1.3 mg

Ages 51+:

Men: 1.7 mg
Women: 1.5 mg

100 mg

Meat, fish, poultry, legumes, tofu and other soy products, potatoes, noncitrus fruits such as bananas and watermelon.

Vitamin B12 (cobalamin)

Helps lower homocysteine levels. Not clear whether it lowers heart disease risk. Assists in making new cells and breaking down some fatty acids and amino acids. Protects nerve cells and encourages their normal growth. Helps make red blood cells.

Adult men and women: 2.4 mcg

Not known

Meat, poultry, fish, milk, cheese, eggs, fortified cereals, fortified soy milk. Vitamin B12 occurs naturally only in animal food sources, so strict vegetarians and vegans should take a multivitamin to get enough.

Vitamin D (calciferol)

Helps maintain normal blood levels of calcium and phosphorus, which strengthen bones. Helps form teeth and bones. Supplements can reduce the number of nonvertebral fractures.

Ages 19–70: 600 IU

Ages 71+: 800 IU

2,000 IU

Fortified milk or margarine, fortified cereals, fatty fish.

Folic acid (vitamin B9, folate, folacin)

Vital for new cell creation. Helps prevent brain and spinal birth defects when taken early in pregnancy; should be taken regularly by all women of childbearing age, since women may not know they’re pregnant in the first weeks of pregnancy. Can lower levels of homocysteine. May reduce risk for colon cancer. Offsets breast cancer risk among women who consume alcohol.

400 mcg

1,000 mcg

Fortified grains and cereals, asparagus, okra, spinach, turnip greens, broccoli, legumes such as black-eyed peas and chickpeas, orange juice, tomato juice.


Helps hemoglobin in red blood cells and myoglobin in muscle cells ferry oxygen throughout the body. Needed for chemical reactions in the body and for making amino acids, collagen, neurotransmitters, and hormones.

Ages 19–50:

Men: 8 mg
Women: 18 mg

Ages 51–70:

Men: 8 mg
Women: 8 mg

45 mg

Red meat, poultry, eggs, fruits, green vegetables, fortified bread and grain products.


Balances fluids in the body. Helps maintain steady heartbeat and send nerve impulses. Needed for muscle contractions. Helps lower blood pressure.

4,700 mg

Not known

Meat, milk, fruits, vegetables, grains, legumes.

Just as a lack of micronutrients can cause substantial harm to your body, getting sufficient quantities can provide a substantial benefit. For example, a combination of calcium, vitamin D, vitamin K, magnesium, and phosphorus protects your bones against fractures. Many micronutrients interact. Vitamin C, for example, helps you absorb iron. The interplay of micronutrients isn’t always cooperative, however. For example, even a minor overload of the mineral manganese can worsen iron deficiency.

Vitamins are different from minerals. A vitamin’s chemical structure can be broken down by heat, air, or acid, whereas minerals hold on to their chemical structure. That means the minerals in soil and water easily find their way into your body through the plants, fish, animals, and fluids you consume. But it’s tougher to shuttle vitamins from food and other sources into your body because cooking, storage, and simple air exposure can inactivate these fragile components.

Your need for certain nutrients varies with your age, gender, and other important characteristics. As a rule, your best strategy is to get vitamins and minerals from food, not supplements. A vast amount of research has shown that you can cut your risk for chronic disease and disability by following a healthy diet, as well as exercising regularly and avoiding smoking. The evidence for taking vitamin and mineral supplements is much less convincing. There are likely many more beneficial components of healthy foods than the ones scientists have identified so far, as well as synergistic effects among them.

Today, many foods are fortified with vitamins to the point where deficiencies are rare. Two important vitamins, Folic acid and Vitamin D have often been singled out by health experts who recommend taking supplements. But the increasing vitamin fortification of the food supply has made even these vitamins so plentiful in food that most people get enough from food. Here are two examples.

Folic acid. One of the most firmly established links between a vitamin and disease prevention involves the B vitamin known as folic acid (also called folate). Women who take folic acid are less likely to have babies with certain birth defects called neural tube defects. Because of this, all women of childbearing age are advised to get 400 micrograms (mcg) daily in foods or supplements to guard against the possibility of birth defects. Some research suggests that women of childbearing age should get 800 mcg per day. You can get this amount through a healthy diet and a daily multivitamin. Most breads and cereals are fortified with folic acid and it is plentiful in some foods including as dark leafy greens, oranges, tomatoes, and legumes.

Vitamin D. This vitamin enables your body to pluck calcium from food sources passing through your digestive tract rather than harvesting it from your bones. It helps prevent osteoporosis and may protect against some cancers and possibly against cardiovascular disease, hypertension, diabetes, and autoimmune disorders.

Exposure to sunlight prompts the skin to manufacture vitamin D, which is why it’s known as the “sunshine vitamin.” The Institutes of medicine recommends all people younger than age 71 get 600 IU per day and people 71 and older get 800 IU per day. Most people can get this amount in food, particularly if they drink milk which is fortified with vitamin D. People who live in northern climates or have dark skin may need supplementation to reach the recommended 800 IU. Do not exceed the Upper Daily Limit of 4,000 IU.

What about antioxidants?

Taking antioxidants in pill form or added to foods doesn’t protect health, according to research. It’s best to get these nutrients in their naturally occurring forms: in fruits, vegetables, and whole grains.

The term antioxidants is a catchall for any compound that can counteract unstable molecules, such as free radicals that damage DNA, cell membranes, and other parts of cells. Free radicals in the body are a natural byproduct of energy metabolism and are also generated by exposure to ultraviolet rays, tobacco smoke, and air pollution. They lack a full complement of electrons, which makes them unstable, so they steal electrons from other molecules, damaging those molecules in the process. Free radicals can be helpful, too. When cells in your immune system muster to fight intruders, the oxygen they use spins off an army of free radicals that destroy viruses, bacteria, and damaged body cells.

Vitamin C can disarm free radicals. Other antioxidant vitamins are vitamin E, beta carotene, and related carotenoids (a class of orange plant pigments). Antioxidant minerals are selenium and manganese. Many antioxidants are chemicals other than vitamins and minerals, including certain pigments and isoflavones. The package of antioxidants found in fruits and vegetables combined with the naturally occurring fiber and phytochemicals in these foods has a variety of healthful benefits, including lowering the risk of heart disease, diverticular disease, and many other conditions.

Taking individual antioxidants in supplement form has not been proven to confer similar health benefits. Findings suggest little overall disease protection from antioxidant pills. It could be that it’s the orchestration of antioxidants naturally present in foods, rather than one or two vitamins in high doses, that can lower your risk of serious illnesses. So it’s worthwhile to get your antioxidants from foods — such as oranges, tomatoes, sweet potatoes, carrots, broccoli, berries, whole grains, and nuts — not from pills.

Fruits and vegetables

We’ve known for decades that fruits and vegetables contain important vitamins, minerals, and other nutrients. Science has also established that a plant-based diet that includes lots of fruits and vegetables can lower your risk of some life-threatening diseases such as heart disease, the nation’s No. 1 killer for both men and women. Moreover, if you pile on the produce, there’s less room for the unhealthy foods.

It’s important to note that even though fruits and vegetables deliver lots of vitamins and other nutrients, you don’t get the same benefits by taking vitamin pills and supplements. Out of hundreds of studies that have tried to separate individual components of foods and determine their specific health effects, only a tiny handful have produced convincing results. Many have fallen flat. Remember when people were taking vitamin E for everything from heart disease to memory loss? How about vitamin C to prevent colds? Or antioxidants to prevent cancer? Promising early evidence has failed to pan out for taking these nutrients in pill form.

Fruits and vegetables contain hundreds of components known as phytochemicals, the majority of which have yet to be identified. These phytochemicals appear in a vast number of combinations in the plants found in nature. Fruits and vegetables are also high in fiber, which serves many functions in the body. In particular, fiber keeps the digestive system running smoothly and may reduce the risk of heart disease, diabetes, some gastrointestinal problems such as diverticulitis (see “The food-health connection”), and obesity. Finally, fruits and vegetables are high in beneficial minerals such as potassium, which lowers blood pressure.

Major studies such as the Nurses’ Health Study and the Health Professionals Follow-up Study have shown that a diet rich in fruits and vegetables can help lower the risk of hypertension, heart disease, and stroke, and that people who follow such a diet live longer than those who don’t. The DASH diet study (see “Eating plans for good health”) directly tested a diet high in fruits and vegetables, and showed a significant blood pressure reduction. People over age 45 had an especially good response to the diet — an important finding because hypertension and its consequences increase with age.

Can a diet high in fruits and vegetables help prevent cancer? So far, it’s not clear. Studies show that such a diet may reduce the risk of some forms of cancer — probably esophageal, stomach, and lung cancers, according to a review of hundreds of studies by the International Agency for Research on Cancer. But a study in TheJournal of the National Cancer Institute involving 400,000 men and women followed over nearly nine years found only a very weak association between fruit and vegetable consumption and a reduced cancer risk.

There is some evidence that eating plenty of fruits and dark green leafy vegetables, such as spinach and collard greens, may lower the risk of macular degeneration, an eye disease that impairs vision. Dark green leafy vegetables have also been linked to a reduced risk of type 2 diabetes.

Such findings give fruits and vegetables a prominent place in the Healthy Eating Pyramid, which recommends eating fruit two to three times a day and eating vegetables “in abundance.” Many experts recommend eating five to 13 servings of fruits and vegetables a day (2½ cups to 6½ cups daily). Yet according to the Centers for Disease Control and Prevention (CDC), only 14% of Americans eat five or more servings daily. A public health campaign, “Fruits & Veggies — More Matters,” aims to close that gap. The campaign, a joint project launched by the Produce for Better Health Foundation and the CDC, suggests eating more fruits and vegetables at every sitting. For more information, see the campaign’s Web site at

Do “local” and “sustainable” mean healthy?

Anything that gets people eating whole foods rather than factory-produced foods is a good thing. While science has yet to prove that a peach grown locally on a sustainable or organic farm is healthier than one shipped in from a faraway country, the interest in local, sustainable agriculture is raising interest in eating healthy, whole, fresh foods.

Sustainable agriculture refers to the use of traditional farming methods to create a self-contained ecosystem that produces food while eliminating artificial fertilizers and pesticides, thereby supporting the environment while encouraging rural farmers’ way of life. Sustainable agriculture cuts down on farms’ heavy petroleum use by setting limits on how far food can be trucked from the farm to market. It also reduces petroleum use by growing crops without pesticides and fertilizers, most of which are derived from petroleum. Sustainable cattle graze on grass, providing natural fertilizer in the form of manure and reducing the need for the antibiotics used heavily for cattle that live in tight quarters and eat grain. Such use of antibiotics encourages the development of powerful strains of resistant microbes, thereby increasing antibiotic resistance in general.

These are positive benefits. But is food produced this way more nutritious? Not enough studies have been done to answer this question, but farming in an environmentally responsible way to conserve natural resources, reduce waste, and lower energy consumption contributes to a healthy planet and therefore to human health over all.

Colorful choices

The vibrant colors of fruits and vegetables are more than just window dressing. Think of the produce department as a store where you shop for a colorful wardrobe: choose lots of different colors for the greatest impact. The reason to choose foods of many colors is that the healthiest diet includes a variety of foods. And when it comes to produce, color is the most outward sign of the different nutrients in different plants. To increase the benefit, choose produce with deep, rich colors like blueberries, carrots, broccoli, and spinach. Fruits and vegetables with deep colors contain the most powerful phytochemicals.

No single type of fruit or vegetable can deliver all the beneficial phytochemicals and other substances. Try to get at least one serving daily from each of the following categories:

  • dark green or leafy vegetables (dark lettuce, kale, spinach, collard greens, broccoli)

  • yellow or orange fruits and vegetables (squash, carrots, nectarines, cantaloupe)

  • red, blue, and purple fruits and vegetables (red peppers, tomatoes, strawberries, blueberries, beets)

  • legumes (lentils and other beans)

  • citrus fruits (oranges, grapefruits, lemons, limes).

For many of us, the words “snack” and “healthy” don’t belong in the same sentence. After all, it’s easy to reach for the chips or candy bars. Regular between-meal snacks are not a necessary part of a healthy diet. Indeed, snacking poses many health risks, such as weight gain and the dangers that go hand in hand with foods high in salt, added sugars, bad fats, and excess calories. With that said, snacking and eating healthfully needn’t be mutually exclusive. It’s possible to make snacks work in your favor. That’s because there are plenty of healthy foods that are quick and easy to eat, such as fruits, veggie sticks, and moderate amounts of nuts.

Even so, if you choose to snack between meals, don’t overdo it. Even healthy snacks can be unhealthful if you eat too much. In general, try to keep snacks to around 150 calories. Eating more calories than you burn each day leads to weight gain, and excess weight is a major risk factor for several life-threatening diseases.

To start snacking well, first survey what’s available. Some snacks are obviously bad for you. Chips and cheese twists are laden with salt, high-glycemic carbohydrates, and sometimes trans and saturated fats. Sweet baked goods — including cookies, snack cakes and bars, brownies, and muffins — are also loaded with bad fats and refined sugars. Candy is mainly sugar and bad fats.

But what about all those fat-free vegetable chips, cereal bars, yogurt raisins, fruit leathers, and organic candies sold in health-food stores and traditional supermarkets — are they harmful? The answer, surprisingly, is that even snacks marketed as healthy, organic, or natural can be unhealthy. Fat-free chips and sweet snacks typically have lots of calories, a high glycemic load (see “What about carbohydrates?”), and few vitamins or minerals. Yogurt raisins sound healthy, but can be packed with bad fats, sugar, and lots of calories per serving. Many baked or fat-free snacks have lots of salt. And an organic chocolate chip cookie is still a high-calorie, sugar-filled cookie. Eating these foods occasionally won’t cause major health problems, but regular snacking of this type will take its toll. Combine that with other occasional treats in the form of desserts and party food, and you’d be surprised how your health can suffer at the hands of occasional indulgences.

Because typical snack foods like chips, candy, and other sweets have a high glycemic load, these foods won’t keep you feeling sated for very long. So you run the risk of reaching for the second or third cookie, thereby overeating, gaining weight, and possibly developing insulin resistance down the road. The same is true if you snack regularly on crackers and pretzels, normally made from refined flours. Foods with high salt content can raise blood pressure, and foods with bad fats contribute to many health problems.

Good snack choices

Good snack choices

What should you eat instead? As a start, try keeping some fresh fruit on your kitchen counter or even in your desk drawer at work. This way, you’ll see it before reaching for the calorie-dense chips or cookies. Bring a banana to work. Keep a bowl of grapes or cherries on the table. Dried fruit can be a good choice if you keep portion size reasonable. Both fresh and dried fruits contain plenty of vitamins and fiber (see Table 5).

Also, try small amounts of unsalted nuts and seeds. Almonds, walnuts, peanuts, roasted pumpkin seeds, cashews, hazelnuts, filberts, and others are good for you for several reasons. They contain many beneficial nutrients and other substances, including vitamin E, folic acid, protein, potassium, and fiber. And although some are high in fat, the fat is mainly unsaturated. Unlike chips and other high-carbohydrate snacks, nuts don’t leave you hungry right away, so you’re less likely to overeat. Nuts have lots of calories, though, so keep portion sizes small. The Healthy Eating Pyramid recommends one to three servings of nuts and legumes a day in meals and snacks combined.

Table 5: Simple switches for healthy eating

Here are some tips for painlessly improving the quality of your diet.

Food ingredients

Instead of these:

Try using these:

Butter, solid margarine, or lard

Olive oil, canola oil, or margarine without trans fats

Cream-based sauces

Tomato-based sauces

Whole eggs

Egg whites or egg substitute

Salt for seasoning

Herbs and spices

Canned vegetables

Fresh or frozen vegetables

Eating habits

Instead of these:

Try these:

Skipping breakfast

Eating oatmeal, whole-grain breads, or bran cereals

Rushing through a meal

Eating slowly

Eating one or two big meals a day

Eating several smaller meals

Sitting on the couch after dinner

Taking a walk


Instead of these:

Try using these:

Corn flakes, Special K, or other refined-grain cereal

Cheerios, Wheaties, or other whole-grain cereal; some granolas are especially healthy because they have nuts and seeds, and less processed grains

Cream of Wheat

Oatmeal (steel-cut oats are best) or other whole-grain breakfast grains.

White rice

Brown rice or other cooked whole grain

White pasta

Whole-wheat pasta

White bread

Whole-grain bread

Full-fat dairy foods

Skim or low-fat dairy foods

Processed meats

Fish, chicken, beans, nuts

Fatty cuts of meat, such as prime rib

Leaner cuts, such as tenderloin (occasionally)

Smoked, cured, salted, or canned meat or fish

Fresh or frozen meat or fish, without added salt

Sugared soda or juice

Water, or juice mixed with sparkling water

Ice cream

Yogurt with fruit

French fries

Roasted vegetables


Instead of these:

Try using these:


Fresh or dried fruit


Nuts, raisins, popcorn without butter (try olive or canola oil), raw vegetables

Soda crackers

Whole-grain crackers without trans fats

Dips high in saturated fats

Hummus, peanut butter, or seasoned low-fat yogurt

Baked goods containing butter or trans fats

Foods baked with healthy fats


Graham crackers or oatmeal cookies with fruit

Dining out

Instead of these:

Try using these:

Super-size entrées

Small- or medium-size entrées

Fried foods

Grilled, broiled, steamed, poached, or roasted foods

Adapted from Eat, Drink, and Be Healthy: The Harvard Medical School Guide to Healthy Eating by Walter Willett, M.D., (Simon & Schuster and Harvard Medical School, 2005).

A snacking strategy

Here’s a good way to make your snack boost your health rather than harm it. Try to eat more than one macronutrient (protein, fat, carbohydrate) at each snacking session. For example, have a few nuts (protein and fat) and some grapes (carbohydrates). Take some whole-grain crackers (carbohydrate) with some low-fat cheese (protein and fat).

If you want to eat chips, look for brands that are free of trans fat and are made with unsaturated fats such as safflower, canola, sunflower, or peanut oil. Even better, choose brands that are “lightly salted” or unsalted. Granola is another good option, especially mixes and bars that are low in sugar and rich in whole grains, nuts, polyunsaturated fats, and dried fruit.

Chocolate lovers can rejoice in the cardiovascular benefits of small amounts of the dark varieties rich in nutrients called flavonoid antioxidants. Chocolate can look nutritiously dark but still be devoid of the healthful flavonoids. To get the most flavonoids, choose high-flavonoid dark chocolate and cocoa products rather than milk chocolate or Dutch processed (alkalized) items. And check the label to be sure. The first ingredient should be cocoa solids, cocoa mass, or chocolate liquor, not sugar.

Choosing snacks with low glycemic load

Typical snack food is full of highly refined carbohydrates in the form of sugar and white flour. Common examples include candy, donuts, cookies, chips, bagels, crackers, snack cakes, and many other foods marketed as snacks. These foods have high glycemic loads and contribute to obesity and the many health problems that go with it, like heart disease, diabetes, and some forms of cancer.

So when snacking, look for non-starchy, non-sugary foods like raw vegetable sticks, bean dips, and fruits such as apples, pears, peaches, and berries. Low-fat yogurt is another good choice. But don’t choose yogurt with “fruit on the bottom” that is basically sugar syrup. Instead, add your own fruit and nuts.

Even tropical fruits like bananas, mangoes, and papayas, which are higher in sugar than other fruits, tend to have a lower glycemic index than sugary desserts like cake and cookies.

Do you like to snack on cookies and crackers? When choosing grain-based snacks, look for the least-processed foods possible. Whole-wheat crackers and natural granola are two possible choices.

Limit white bread and crackers and white rice cakes. Choose whole-grain versions instead.

For your drink, soda is well known to have too much sugar. But did you know that many fruit juices are also high in sugar (see Figure 2)? Reduce your fruit juice consumption to no more than one cup a day. Completely eliminate drinks with added sugars, such as sodas. Water is a good choice, as is seltzer, or a cup of tea or coffee.

Eat slowly, and stop when you’re full.

Ten tips for healthy snacking

Snacking isn’t necessary for healthy eating, but if you know you are likely to snack between meals, here are 10 ways to have your snack and eat it healthfully.

1. Keep junk food out of the house. At home, you won’t eat what isn’t there. Or, if someone in your household tends to have chips or ice cream around, put them out of sight.

2. Stop and snack mindfully. Don’t eat your snack while doing something else like surfing the Web, watching TV, or working at your desk. Instead, stop what you’re doing for a few minutes and eat your snack like you would a small meal.

3. You can take it with you. Think ahead and carry a small bag of healthful snacks in your pocket or purse so you won’t turn in desperation to the cookies at the coffee counter or the candy bars in the office vending machine.

4. Go for the grain. Whole-grain snacks, such as whole-grain low-salt pretzels or tortilla chips and high-fiber, whole-grain cereals, can give you some energy with staying power.

5. Mix and match. Try baby carrots or other raw veggies with yogurt. Dip wheat crackers in guacamole.

6. Broaden the menu. Seek out some out-of-the-ordinary snacks or fruits like pomegranates, red or yellow peppers, mangoes, tangelos, or roasted unsalted soy nuts.

7. Revisit breakfast. Many breakfast foods can be repurposed as a nutritious snack later in the day. How about a slice of whole-grain toast topped with low-sugar jam? Low-sugar granola also makes a quick snack.

8. Try a “hi-low” combination. Combine a small amount of something with healthy fat, like peanut butter, with a larger amount of something very light, like apple slices or celery sticks.

9. It’s in the seed. Seeds, so long as they are unsalted, are nutritious and healthy and stick with you. Try sunflower seeds with some apple slices to add some juicy sweetness.

10. Spice it up with mustard. Flavorful and low-calorie, mustard can enliven otherwise dull snacks like whole-wheat crackers or pretzels.

Are there foods you never should eat? Not really. If you crave an ice cream sundae occasionally, have a small one. But don’t make it a daily event. If you eat chips at your neighbor’s backyard party, choose healthier snacks at home. Healthy eating is not like many of the popular weight-loss plans that require you to eliminate certain foods entirely. But there are some foods you should eat only rarely.

Harvard nutrition scientists have compiled the following list of foods to keep to a minimum because research strongly shows that consuming these foods regularly — more than other foods — can promote life-threatening illnesses such as heart disease, hypertension, diabetes, and even cancer (see “The food-health connection”).

Added sugar

Whether it’s white granulated sugar, brown sugar, high-fructose corn syrup, corn sugar, or honey, sugar contains almost no nutrients other than the sugar itself, pure carbohydrate. Sugar isn’t dangerous per se, but a heavy sugar intake increases your diet’s glycemic load, fills you up with empty calories, and keeps you from eating healthy foods that contain vitamins, minerals, fiber, and other nutrients. Want evidence? Give a child a sugary drink right before dinner, and most of the meal will stay on the plate. Cutting back on candy, soda, and other sweets is just half the battle, however. There’s lots of hidden sugar in prepared foods, including fat-free snacks and cereal bars. Look for sugar in surprising places such as peanut butter, ketchup, and spaghetti sauce. Even prepared frozen entrées have added sugars. What’s more, snacks that contain good ingredients such as whole wheat, canola oil, and olive oil are no longer as healthy once they’re loaded with sugar.

Here’s your chance to make a big difference in your calorie intake, your weight, and your health. Ask yourself: is this food naturally sweet, or did someone add sugar or honey to make it sweet? Try not to add sugar or honey to tea, coffee, or cereal. Read the labels on packaged foods, and steer clear of foods that have sugar, honey, corn syrup, corn sugar, fructose, or high-fructose corn syrup among the first three ingredients. Other sugar aliases to watch for include agave nectar, brown sugar, cane sugar, corn sweetener, dextrose, maltose, fruit juice concentrate, and glucose.

Despite what you may have heard or read, high-fructose corn syrup, which is widely used in many products, doesn’t seem to be any better or worse for you than any other kind of added sugar. This sweetener has developed such a negative reputation that the Corn Refiners Association has petitioned the FDA to allow a name change to “corn sugar” on ingredients lists. There’s a slight difference between various types of sugar. Table sugar, generally produced from cane plants or beets, is made of one glucose molecule joined to one fructose molecule, so it contains glucose and fructose in equal proportions. High-fructose corn syrup, or corn sugar, also contains glucose mixed with fructose, with just slightly more fructose than glucose. Since table sugar and high-fructose corn syrup are made up of glucose and fructose in roughly similar proportions, it’s likely that both forms of sugar have a similar physiological impact on blood sugar, insulin, and metabolism.

Fast fact

Food manufacturers often make sure sugar doesn’t appear first on the ingredients list by using two or more types of sugar, listed separately; thus, when the ingredients are ranked in order of weight, other ingredients appear first. Avoid foods with several different forms of sugar listed.

Dairy fat

Ice cream, whole milk, and cheese contain a lot of saturated fat and some naturally occurring trans fat and therefore can increase the risk of the health problems traced to bad fats, notably heart disease. The healthiest milk and milk products are low-fat versions, such as skim milk, milk with 1% fat, and reduced-fat cheeses.

Baked sweets

Cookies, snack cakes, doughnuts, pastries, and many other treats are hard to pass up, but they are the very definition of the modern food crisis because the commercially prepared versions are packed with processed carbohydrates, added sugar, unhealthy fats, and often salt.

Doughnuts, for example, are cakes fried in fat and have large amounts of saturated fat, sugar, and calories. But doughnuts present additional problems. For one thing, they’re often eaten for breakfast, replacing what could be a nutritious meal. Second, because doughnuts are often purchased by the dozen, you may be tempted to eat two or more in one sitting. If you’re a doughnut lover, you can improve your diet by eating doughnuts only for dessert, limiting yourself to just one, and making them only an occasional treat. A single doughnut has around 250 calories with 40% from fat — mostly saturated fat.

Other pastries, cookies, pie, croissants, tarts, cake, and Danish have similar issues. Pastries are, by definition, baked goods made with high-fat dough and lots of added sugar. As any chef will tell you, it’s the butter or lard (both saturated fats) or shortening (trans fat) that’s the key to making flaky crusts. And many pastries are topped or filled with buttercream, whipped cream, or icing — each packing a wallop of saturated fat and trans fat (especially in store-bought goods), sugar, and calories. A slice of cheesecake can have 800 calories or more — a large share of the 2,000 to 2,500 you need in a day. Instead, go for the fruit plate or even biscotti, Italian almond cookies made without butter or oil.

White carbohydrates

Whether it’s bread, pasta, potatoes, rice, cookies, cake, or pancakes, it’s best to look for the whole-grain version. Yes, you can find or make whole-grain pancake mix. Whole-wheat pastas and breads are luckily easy to find. And you can always make your own homemade cookies or bars using grains such as oatmeal, and less sugar and unhealthy fats.

Other foods that come in whole-grain versions are muffins, croissants, crackers, bagels, and other baked goods made with white flour. Unless you choose the whole-grain versions, count these among the bad carbohydrates because of their fairly high glycemic load and very little fiber.

Processed and high-fat meats

Shun the cold cuts and “pigs in a blanket” when snacking. Head instead for the vegetable plate. Despite some conflicting reports, the balance of the evidence confirms that processed meats like bacon, ham, pepperoni, hot dogs, and many lunch meats are less healthy than protein from fish, skinless chicken, nuts, beans, soy, and whole grains. Fresh red meat should be eaten sparingly and the leanest cuts selected (see “Choosing meat and fish”). Also, meat is healthier when cooked in ways that don’t char the meat, such as baking or stewing. As noted earlier, browning meat by searing it on the grill or stovetop or under the broiler creates carcinogens. In addition to heterocyclic amines, carcinogens called polycyclic aromatic hydrocarbons (PAHs) can also form when fat and juices from meat drip down to the heat source of the grill, resulting in smoke. The smoke contains PAHs. As the smoke rises up past the food, the PAH compounds can be deposited on the surface of the meat.

Sugary beverages

Research at the Harvard School of Public Health and elsewhere has tied sugary drinks to the obesity epidemic in the United States. Currently, about two-thirds of Americans are overweight or obese. Obesity raises the risk of type 2 diabetes, heart disease, arthritis, and certain cancers. Research cites soft drinks and other sugar-sweetened beverages as the primary source of added sugar in the American diet and a major contributor to weight gain. In fact, downing just one extra 12-ounce can of a typical sweetened beverage daily can add on 15 pounds in a year. That’s not only because the drinks themselves add calories, but also because those liquid calories aren’t as satiating as solid food. According to the American Heart Association, drinking a sugar-sweetened beverage makes you consume more calories in general. And the more you drink, the more you eat. In one study, when the size of a regular soda increased from 12 to 18 ounces, men and women ate 26% and 10% more calories from food, respectively.

A study also linked sugary drinks to an increased risk of heart disease in adults. In addition to raising blood glucose, insulin, and triglycerides, sugar reduces the “good” HDL cholesterol in the blood. Consistent with this effect, the study showed that it wasn’t just weight gain but sugar itself that raised heart disease risk.


Salt contains sodium. The current dietary guidelines and the American Heart Association recommend reducing sodium to 1,500 mg per day and not exceeding 2,300 mg per day. But most of us get 1½ teaspoons/8,500 mg of salt daily, which translates to about 3,400 mg of daily sodium. Your body needs sodium to make your muscles contract, to help nerves conduct impulses, and to maintain a healthy balance of fluids. Too much sodium, though, can increase blood pressure and the risk of heart disease and stroke. People over age 50, African Americans, and women are particularly susceptible to getting high blood pressure from a salty diet. How much good can eating less salt do? A study in The New England Journal of Medicine predicted that reducing daily salt intake by 3 grams (1,200 mg) would reduce the annual number of new cases of heart disease, heart attack, and stroke by about a third.

Despite 50 years of warnings, Americans have not reduced their salt consumption. A 2010 study by Harvard researchers concluded that salt consumption is nearly the same as it was 50 years earlier.

Where is all that salt coming from? Up to 75% of the salt in the American diet comes not from the salt shaker, but from processed foods such as chips, processed cheese, and many canned and prepared foods or restaurant foods. What’s even more surprising is that many foods that are high in sodium don’t even taste especially salty. Who would guess that a tuna sandwich has 1,300 mg of sodium or that a cup of cottage cheese packs 900 mg?

Tips for reducing sodium

Following the Dietary Approaches to Stop Hypertension (DASH) diet has been shown to lower blood pressure and reduce the risk of heart disease and stroke. The DASH diet (see “Eating plans for good health”) is high in fruits, vegetables, and whole grains; moderately high in nuts and low-fat dairy products; and low in red and processed meats and sodium. Here are some additional ways to stop the salt assault and slash the sodium from your meals and snacks.

  • Choose unprocessed and minimally processed foods. By choosing fresh foods and limiting the use of canned, processed, and frozen foods, you can control your own salt consumption.

  • When you do buy processed foods, choose foods low in sodium by reading food labels. Sodium is usually listed after total fat and cholesterol. Choose items in which the sodium content is less than or equal to the calories per serving.

  • Drain and rinse canned foods.

  • Reduce your consumption of the highest-sodium foods such as pepperoni pizza, white bread, processed cheese, hot dogs, spaghetti with sauce, ham, ketchup, cooked rice, white rolls, and flour tortillas. They’re the top 10 food sources of sodium in the American diet.

  • When eating out, ask your server to recommend foods prepared with less salt. Check restaurant Web sites for sodium information before you eat out. Some chain and fast-food restaurant dishes can top 5,000 to 6,000 mg of sodium per serving. Also, downsize your portions by skipping the super-size or sharing a dish. As a general rule, the more calories a meal has, the more sodium it has. Cut your salt and — bonus — trim your waist.

  • Save your “sodium budget” of 1,500 mg/day to enhance the flavor of produce, whole grains, nuts and legumes, and other healthy ingredients instead of blowing the budget on salty snacks, heavily processed food, high-sodium fast foods, and other foods that we all should be consuming in smaller amounts. Think of high-salt foods as a treat, much like you probably do dessert.

  • Train your taste buds. A study published in the September 2007 Journal of the American Dietetic Association found that people like lower-sodium foods just as much as food with the common sodium overload. It is possible to shift your sense of taste to enjoy foods with lower sodium. Make these changes gradually and consistently over time and you’ll find that you won’t miss the salt.

The foods you eat every day can have a tremendous effect on your health. Decades of research have produced study after study showing links between diet and serious illness. A healthy diet has the power to prevent heart disease, hypertension, diabetes, gastrointestinal disorders, some forms of cancer, blindness, and birth defects. It does matter whether your breakfast is a doughnut or a bowl of steel-cut oats, whether your sandwich is ham and cheese or hummus and tomato, and whether dinner is steak or salmon. Dozens of other food choices you make can affect how long — and how well — you live. In particular, eating no more calories than you burn each day is important.

The following sections describe common health conditions that are influenced by your diet. For each disease, you’ll find a list of foods and nutrients that can lower your risk of developing that disease as well as a list of foods or food components that can raise your risk.

Hindering heart disease and stroke

Your diet: Heart disease

Good choices

  • Fruits and vegetables

  • Monounsaturated and polyunsaturated fats (olive oil, canola oil, soybean oil, safflower oil, nuts, seeds)

  • Omega-3 fats (fish oil)

  • Fish

  • Whole grains

Risky choices

  • Processed and cured meats, butter, and full-fat dairy products

  • Trans fats (partially hydrogenated oils)

  • Salt

  • Dietary cholesterol

  • Excess intake (more than 65% of calories) of carbohydrates with a high glycemic load

For many years, it was an article of faith that following a low-fat diet reduced your risk for heart disease and possibly stroke. Stroke, like coronary artery disease, is most often caused by a blockage of blood vessels delivering oxygen to vital tissues. But further research has shown that certain healthy fats — mainly from vegetable sources — can reduce your risk of heart attack and stroke. For people with heart disease, clinical trials show a heart-healthy diet that includes these fats saves as many lives as heart medication.

The first hint that some fats are healthier than others came from the Seven Countries Study, an international diet survey conducted in the 1960s. This study produced the surprising news that the region with the lowest incidence of heart disease — Crete — also had the diet with the highest fat content — about 40% of calories. This fat came mainly from vegetable sources like olive oil. In 1997, the Nurses’ Health Study looked at the relationship between the diets of more than 80,000 women and the health problems they developed. There was absolutely no connection between how much total fat the women ate and whether they eventually developed heart disease. But the type of fat did make a difference. The women with the highest incidence of heart disease ate the most saturated and trans fat. Meanwhile, the women with the lowest incidence of heart disease had diets that were low in trans fat but relatively high in polyunsaturated fat, which comes primarily from vegetable oils. Again, in 2006, the Women’s Health Initiative demonstrated that a diet low in total fat didn’t protect against heart disease.

Heart-healthy fats

Reach for the vegetable oils. Foods made with either polyunsaturated or monounsaturated fat are your best choice. On the other hand, saturated fat and trans fat increase your risk of heart disease by raising blood cholesterol, especially LDL cholesterol, the type that promotes heart disease. They also boost the levels of triglycerides, another type of fat in your blood that is linked to heart disease. And even worse, trans fat lowers your levels of HDL cholesterol, the good cholesterol that helps protect against heart disease (see “All about fat”). If you use margarine, choose a heart-healthy variety made with little or no trans fat or saturated fat.

Research shows that it’s healthier to replace bad fats with good fats (poly- and monounsaturated fats) than it is to cut back on all fats in your diet. That’s because simply reducing fats across the board lowers your healthy HDL cholesterol as well as the damaging LDL cholesterol, and it raises triglycerides. It’s like cutting down the whole tree just to get rid of some bad apples. Ideally, you want to keep LDLs low and HDLs high, and that’s what the good fats help do. When you replace unhealthy saturated and trans fat with healthy monounsaturated and polyunsaturated fats, LDLs drop more than beneficial HDLs.

Other positive effects come specifically from omega-3 and omega-6 polyunsaturated fats, found in fish, many vegetable oils, and some nuts and seeds. These fats reduce triglycerides, prevent arrhythmias (abnormal heartbeats), lower blood pressure, and help prevent atherosclerosis. Omega-3s and omega-6s both reduce the risk of heart disease and stroke. Fish, in particular, offers potent protection against the most common type of stroke — ischemic stroke, which is caused by blockages in the arteries to the brain. In 2002, the Health Professionals Follow-up Study found that men who ate fish at least once a month were 43% less likely to have ischemic strokes compared with men who never ate fish. Women in the Nurses’ Health Study who ate fish were also less likely to have strokes than those who didn’t.

Monounsaturated fats haven’t been shown to reduce the risk of heart disease, but they do lower LDLs, which means that they’re good for the heart. The liberal use of olive oil in Mediterranean countries contributes to the very low rates of heart disease there.

What does all this mean for you? To reduce your risk of heart disease, replace dangerous saturated fats and trans fats with beneficial polyunsaturated fats, including fish oil, and monounsaturated fats.

Carbs and fiber

When you cut down on the saturated and trans fat in your diet, make sure you don’t overeat carbohydrates to compensate for missing fat calories. If you fill up on rapidly digested carbohydrates such as sugar, white bread, potatoes, white pasta, or white rice, not only can this contribute to weight gain, but over time it can cause a dangerous rise in triglycerides in your blood and cause your blood sugar to rise too rapidly.

Instead, eat plenty of good fats and proteins, and get most of your carbohydrates from whole-grain foods, such as whole-wheat cereals and breads, as well as fruits and vegetables. Whole grains clearly protect against heart disease and stroke, perhaps because they contain fiber, magnesium, folate, and vitamins B6 and E. The fiber in whole grains helps lower cholesterol and may increase the body’s anticoagulant activity, which helps prevent the formation of blood clots that can cause heart attacks and strokes. But fiber can’t do it all. Studies show that even when fiber intake is high, overweight and obese women have an increased risk of heart disease if they’re eating a high-glycemic diet. Choose a diet that has lots of vegetables, olive oil, fish, fruits, and nuts but less processed meat and dairy.

Healthy today, harmful tomorrow?

Good science nurtures hunches and takes chances. But even the most promising ideas must work their way through a hierarchy of studies before scientists can draw firm conclusions. To be considered reliable, findings must be reproduced by other studies and in different groups of people. In the process, the findings of seemingly reliable studies can be reversed by newer research. This can be frustrating for people trying to make healthy choices.

To make sense of conflicting reports, think of scientific studies as a balance scale. Some studies will report that a particular food is useful for preventing disease and others will say it’s not. But as more studies are published and the weight of the evidence mounts, the scale will tip in one direction or another, favoring one set of conclusions.

Besides the quantity of studies, consider the type of study being reported. Gaining an understanding of the different types of research and which types are most trustworthy can help you decide how much weight to give reports of studies on food and health.

  • Give the lightest weight to laboratory studies. Experiments done in test tubes or laboratory trials involving animals can suggest how and why the underlying biochemistry might work, but the findings may not automatically translate to people.

  • Observational studies of people, in which researchers follow large groups, often for decades, command a moderate amount of weight. Examples include the Women’s Health Initiative, the Nurses’ Health Study, and the Health Professionals Follow-up Study (all cited in this report). Using questionnaires and other methods, scientists collect data at regular intervals as thousands of participants simply live their lives. Most risk factors cannot be tested directly in people, but by comparing those who stay healthy with those who fall ill, scientists try to identify factors that could account for the difference. This category includes the types of epidemiological studies called cohort, longitudinal, prospective, and case-control studies.

  • Give the most weight to experimental studies in people. In these, the researchers control what happens. In the case of nutrition and health studies, that usually means testing a diet or behavior change. Often called clinical trials, experimental studies start small and, if successful, are repeated with more and different groups of people. Within this category are randomized controlled trials. If conducted properly, these are considered the gold standard — the most credible studies of all. Volunteers participating in these trials are randomly assigned either to a group that tests an experimental drug, a food, a dietary supplement, or another treatment, or to a control group whose members receive a placebo or standard treatment or diet for comparison. If possible, both the volunteers and the researchers are “blinded,” meaning they don’t know who is in which group until the end of the study.

The media cover all types of intriguing studies, but reporters sometimes fail to put a study in context by explaining the type of research reported and what kind of questions it can honestly answer. Exciting new findings make headlines, often creating a misleading impression that the results are definitive. Also, studies often make the news precisely because they contradict a larger body of evidence, which may remain more convincing despite a single clashing new finding.

One helpful analysis growing more popular in nutrition studies is called a systematic review. In these, researchers conduct comprehensive searches of previous studies, evaluate the best-quality evidence, and summarize large amounts of information. They are published in journals and available from other sources, such as the Cochrane Library and the U.S. Agency for Healthcare Research and Quality. If the studies are similar enough, researchers may conduct a meta-analysis, which combines and reanalyzes the data from several studies.

Even when you do know how much relevance a study commands, news articles may include little about the quality of the research. Moreover, each type of study faces its own set of challenges and limitations. Here are just a few:

Observational studies often suggest a link between a nutrient and a certain disease. But they can’t say whether the nutrient actually caused or prevented the disease. Beware of headlines that indicate otherwise: “Soy protects heart,” “Red meat causes cancer,” and so on. These results can be tainted by something called “recall bias.” That is, when ill participants are asked to describe their diet, they often recall a worse diet than the one they actually followed. Healthier folks, meanwhile, tend to see their diets through rose-colored glasses. Routine questioning of the same people over time can avoid recall bias, but these studies require large numbers, take a long time, and sometimes rely on imprecise questionnaires. Also, a nutrient found to be related to disease may also be just a marker for another nutrient in the food that is more important. That is considered a potential explanation for why some supplements like antioxidant vitamins have failed to prevent disease when put to the test of a clinical trial, whereas there is better evidence for foods that just happen to be rich in these vitamins.

Metabolic studies, a type of clinical trial, typically involve a small number of volunteers who eat specially prepared meals for short time periods and are tested at regular intervals. These studies are rigorous and closely controlled. They show effects on risk factors like blood pressure and cholesterol, but are usually too brief to show actual prevention of disease.

Randomized controlled trials, another type of experimental study, also have their potential problems. First, they may be too short to reveal a nutrient’s long-term consequences. Also, these studies may involve participants who are in better or worse health than you are. And because of limited knowledge about a disease (for instance, cancer), randomized controlled trials may not introduce the dietary intervention when it could have done the most good. Last, these trials can be extremely difficult to conduct because researchers have to control the behaviors of large numbers of people, often for many years. If participants don’t stay with the assigned treatment, findings could be blurred or even lost.

Systematic reviews often pool results of all available observational or experimental studies, but like other forms of research, they vary in quality. They are only as good as the studies that have been included. They can often answer only very narrow questions. And they may have personal or funding biases just like any other study. So, the bottom line is to read reports of nutrition news skeptically, and consider whether the weight of evidence from a series of solid studies warrants making any changes in your eating habits.

It’s also important to consider whether the possible benefits to your health outweigh potential risks. Before making a change, get more information. Reputable sources of health information put key studies in perspective for you. Your doctor’s advice can be valuable, too.

Halting hypertension

Your diet: Hypertension

Good choices

  • Fruits and vegetables

  • Fish

  • Nuts

  • Low-fat dairy products

  • Potassium-rich foods

Risky choices

  • Salt and salty foods

  • Processed and cured meats

  • Saturated and trans fats

  • Sugary foods and drinks

About half of adults in the United States, and 80% of those over age 50, have blood pressure high enough to put them at risk for heart disease and stroke. A healthy blood pressure is 120/80 millimeters of mercury (mmHg) or lower. The higher your blood pressure, the greater your risk.

Salt. Diet has a big impact on blood pressure. In particular, salt consumption plays a role, as does obesity. Americans eat far more salt than they should, most of it coming from processed, packaged foods rather than from foods prepared at home.

Every day, the average American takes in about 1½ teaspoons (8,500 mg) of salt — which translates to about 3,400 mg of sodium. That’s 50% higher than the maximum of 5,700 mg of salt (2,300 mg of sodium) advised by the federal Dietary Guidelines for Americans, and double what the American Heart Association recommends (3,800 mg of salt, or 1,500 mg of sodium) for people ages 40 and older or those with borderline high blood pressure, heart conditions, kidney trouble, or diabetes. Research shows that the sodium in salt can raise blood pressure in many people and suggests that reducing salt intake may help offset the natural rise in blood pressure that occurs with age.

A low-salt diet can be achieved by eating more unprocessed fruits, vegetables, and grains. A healthy diet can reduce blood pressure enough that many people with mild hypertension can try diet modification (along with other lifestyle changes) instead of blood pressure drugs. If you’re already taking blood pressure drugs, healthy eating could enable you to reduce the dose or the number of drugs you take. The DASH diet (see “Eating plans for good health”) was the first diet plan shown to reduce high blood pressure. One reason the DASH diet and related DASH-style eating plans work is that they’re rich in potassium, a mineral known to lower blood pressure. Potassium is found in many fruits and vegetables, including bananas, melons, and avocados. Reducing salt intake enhances the effect.

Eating plans for good health

The Mediterranean diet. The traditional Mediterranean diet of the 1960s was abundant in minimally processed plant foods such as grains, beans, nuts, dates, vegetables, and fruit. People in this region typically consumed dairy in moderate amounts and drank wine with meals. In coastal regions, fish was a mainstay. Red meat was consumed only occasionally. Olive oil was liberally used. Dessert was typically fruit.

DASH-style diets. DASH-style diets are eating plans that are rich in fruits and vegetables, moderate in low-fat or nonfat dairy foods, and low in sodium and sweets. These diets also include grains, especially whole grains; lean fresh meats, fish, and poultry; and nuts and beans. The original DASH eating plan was shown to lower cholesterol and make it easy to lose weight. It is a healthy way of eating, designed to be flexible enough to meet the lifestyle and food preferences of most people, and it contains all the healthy foods from the Mediterranean diet. Newer versions of the DASH plan have been created as dietary science learned that it was not the amount of total fat but the kind of fat that made a difference to health. Research shows that diets rich in unsaturated fat (from plant oils, nuts, and whole grains) and high in proteins can be heart-healthy because they improve cholesterol and blood pressure levels. The newer DASH-style diets incorporate these findings and include healthy forms of fat; meats are limited to lean cuts and skinless poultry.

To obtain more detailed eating plans for these diets, see:

Weight. Being overweight increases the risk of high blood pressure approximately threefold. The risk continues to rise as body mass index (BMI) progresses into the obesity range. However, systolic and diastolic blood pressures drop an average of 1 mm Hg for roughly every pound of weight lost, although the actual amount varies widely from person to person. What’s a healthy weight for you? Let the BMI guide you. A BMI of 25 to 29 indicates that an individual is overweight, while a BMI of 30 or above designates obesity.

Another thing to keep in mind is that it’s not weight alone that matters, but also where you carry your extra weight. People with excess fat in the abdominal area are not only at greater risk for hypertension, but also for high cholesterol and diabetes. So if your BMI is 25 or more, and especially if you have accumulated abdominal fat, the unfortunate reality is that you need to lose weight.

Alcohol. Modest alcohol consumption appears to help prevent heart disease, but the key word is modest — no more than one drink a day for women or two for men; heavier drinking increases blood pressure and interferes with blood pressure medication. Don’t let one drink turn into more. And avoid binge drinking (consuming five or more drinks in several hours) even if it’s only now and then. Drinking several drinks in a row negates alcohol’s cardio protection, according to meta-analyses in the December 2009 American Journal of Epidemiology. Alcohol also adds “empty” calories that can contribute to weight gain.

Exercise. Regular exercise not only helps prevent weight gain and high blood pressure, it’s a proven treatment for existing hypertension. Moderate-intensity training (such as walking or riding an exercise bike) seems to be at least as good for blood pressure as high-intensity exercises like running.

Defeating diabetes

Your diet: Diabetes

Good choices

  • Whole grains

  • Fiber

  • Fruits and vegetables

  • Polyunsaturated fats

Risky choices

  • Excess calories

  • Added sugars

  • Refined starches

  • Saturated and trans fats

Diabetes is three times as common today as it was in 1960. That’s particularly bad news not only because diabetes is a life-threatening disease in its own right, but also because it increases the risk for cardiovascular disease, kidney disease, and possibly colorectal cancer. It may also contribute to memory loss, and other kinds of mental deterioration. Diabetes is a condition in which the body can no longer produce enough of the hormone insulin to lower blood sugar to normal levels. In non-insulin-dependent diabetes, also known as type 2 diabetes, the cells in muscles, liver, and fat gradually become less responsive to insulin, so the body can’t properly use the insulin it does produce. This decline in responsiveness, called insulin resistance, is caused in large measure by a poor diet, excess weight, and lack of exercise.

The good news is that, according to research, type 2 diabetes can be prevented with healthier eating habits and regular exercise. A 2009 Lancet study on the Diabetes Prevention Program, a randomized clinical trial that tracked diabetes incidence in 2,766 high-risk adults for 10 years, found that lifestyle changes — a healthy diet, exercise, and weight loss — were more effective at delaying the onset of diabetes than drug intervention.

Weight. The single biggest risk factor for type 2 diabetes is obesity. It’s no coincidence that the rates of both diabetes and obesity have soared since the 1970s; most experts believe it’s the increase in obesity that has triggered the increase in diabetes. Over half of the women and men in the United States are either overweight or obese, according to the CDC. Three-quarters of all people with type 2 diabetes are or have been overweight. Overeating in general can cause type 2 diabetes, but certain types of foods in particular can also affect your risk.

Glycemic load. The leading dietary villains in diabetes appear to be carbohydrates with a high glycemic index (see Table 1). Several studies show that people whose diets have the highest glycemic load (large amounts of sugars and white starches) also have the greatest risk of diabetes, suggesting that eating lots of foods with a high glycemic load probably contributes to the development of diabetes.

Foods with a high glycemic index can promote diabetes in two ways. First, they have a roller-coaster effect on blood sugar. That is, they leave you feeling hungry shortly after you eat, which can lead you to eat again and ultimately gain weight. In addition, a steady diet of foods with a high glycemic load may cause diabetes by setting up a cycle of repeated surges of blood sugar and excess insulin production. The more foods you eat that have a high glycemic load, the more likely you are to overload your blood with sugar, spurring your pancreas to pump out large amounts of insulin. This cycle may ultimately wear down the cells that make insulin, causing insulin output to drop and resulting in high blood sugar, a hallmark of diabetes.

Foods that protect against diabetes. Three types of foods have shown some promise in guarding against the development of diabetes: high-fiber cereals, polyunsaturated fats, and, of course, foods with a low glycemic index, such as green leafy vegetables. Surprisingly, coffee may also help reduce risk. A 2005 JAMA study found that people who drank 4 to 6 cups a day had a 28% lower risk of type 2 diabetes compared with those who drank less than two daily cups. A small amount of alcohol appears to be beneficial, too. In the Nurses’ Health Study, the risk of diabetes was low among women with a very specific dietary profile: they ate a lot of these beneficial foods and very few saturated fats, trans fats, and foods with a high glycemic index. Women with these eating habits who had normal weight, exercised for at least half an hour a day, didn’t smoke, and had at least half a drink of alcohol each day had a risk of diabetes that was a mere one-tenth that of women who didn’t do these things. In other words, 90% of cases of diabetes could be prevented with a healthy diet and lifestyle, including exercise.

Treating existing diabetes with diet alone does not appear to be effective. In fact, there are no high-quality data showing that diet alone will effectively treat or prevent type 2 diabetes, concluded a 2007 Cochrane systematic review of 18 of the best studies to date. For people who already have diabetes, today’s experts recommend a diet that protects against heart disease and obesity as the best choice. That means limiting foods with saturated and trans fats, such as meats, particularly processed meats, and high-fat dairy products and commercial baked goods like cookies, chips, and cakes. Eat fewer refined starches and sugars, and eat more whole grains, fiber, fruits and vegetables, and nuts. Combine that with regular exercise and weight loss, and you have a prescription for improvement.

Battling breast cancer

Your diet: Breast cancer

Good choices

  • Folic acid (folate) for women who consume alcohol

Risky choices

  • Alcohol

  • Excess calories

  • High soy intake (uncertain)

Despite years of research on the topic, the connection between food and breast cancer remains unclear. Regarding fruits and vegetables, for example, studies have revealed little protective effect. Most experts now think that hormones have a much greater effect on breast cancer risk than diet does.

For example, in a major analysis of several studies of large groups of women, those who ate the most fruits and vegetables had about the same risk of developing breast cancer as those who ate the least. More recently, a diet high in vegetables, fruit, and fiber and low in fat didn’t prevent further breast cancer or death in early-stage breast cancer survivors over a seven-year follow-up period, reported a 2007 study in JAMA.

Hormones. The key to breast cancer seems to be factors that raise a woman’s exposure to hormones, particularly estrogen, over a lifetime. Early age at first menstruation, less time spent breast-feeding, later age at first pregnancy, use of postmenopausal hormones, weight gain after menopause, and sedentary living all seem to raise the risk of developing breast cancer. Taller women also seem to have higher risk of developing breast cancer. But height is not the cause of this increased risk. Instead, height is an indicator of other factors, including hormonal factors, that promote growth in childhood.

Dietary fat. One of the most-studied questions in the diet–breast cancer connection is the role of dietary fat. Scientists became interested in this question when international studies showed that women in countries where fat consumption was low had low rates of breast cancer. Not only that, but when women migrated to the United States, where fat consumption is high, breast cancer rates rose both for the women who migrated and for their daughters.

In 1989, the National Academy of Sciences recommended cutting fat from the diet as one of the best ways to prevent breast cancer, as well as colorectal cancer and prostate cancer. Later studies didn’t confirm the idea that a high-fat diet contributes to breast cancer, and the connection between diet and breast cancer appeared weak. In particular, the large Nurses’ Health Study hasn’t found a link between fat consumption and breast cancer. Then, in 2006, authors of the randomized Women’s Health Initiative dietary modification study suggested that a slight trend toward lower breast cancer rates in women on a low-fat diet might become more solid if the women were followed longer. However, women on low-fat diets lost about 5 pounds, so the lower breast cancer rates may have been the result of losing weight rather than eating less fat. The same year, another randomized trial in women treated for breast cancer, the Women’s Intervention Nutrition Study, credited modest weight loss (6 pounds), not lower dietary fat, with a small reduced risk of recurrence.

Calories and body fat. Body fat, unlike fat in the food you eat, seems to have a stronger link to breast cancer. Studies of animals as well as humans consistently show that eating too many calories increases the risk of breast cancer and that reducing calories seems to lower breast cancer risk. Animal research suggests that calorie restriction might slow down cell division, a hallmark of cancer, and inhibit tumor growth. In laboratory animals, cutting daily calories by 30% reduced mammary cancer rates by as much as 80%.

General fatness and belly fat also are probable risk factors for postmenopausal breast cancer, but not premenopausal breast cancer. Your risk of postmenopausal breast cancer increases by about 10% with every 11 pounds you tack on to your frame. Researchers think this occurs because fat cells contain the enzyme aromatase, which converts other hormones into estrogen, a known promoter of breast cancer. In one large study, postmenopausal women who gained the most weight were more than twice as likely to develop breast cancer compared with women who gained no weight or lost weight.

Exercise. Similarly, exercise seems to be more important in postmenopausal women in lowering the risk of breast cancer than in younger women, with lowered risk proportional to the hours of activity every week.

How does all this information translate to practical, daily eating patterns that might help reduce breast cancer risk? Aim for a BMI in the range of 19 to 24. If you need to lose weight, strive to burn more calories than you consume by eating less and exercising more. That basic weight-loss recipe for success was underscored in a 2009 New England Journal of Medicine study in which participants with a BMI between 25 and 40 were put on diets with varying levels of fat, protein, and carbohydrates. They also burned 750 more calories than they consumed each day. After two years, everyone lost similar amounts of weight, which solidified the fact that a diet with fewer calories — no matter whether it’s higher in protein, fat, or carbohydrates — leads to weight loss.

Alcohol and folic acid. Several large studies showed that having two drinks a day increased a woman’s risk of developing breast cancer by 20% to 25%. A larger analysis of seven major population studies found that drinking one glass of any kind of alcohol per day increased a women’s risk of breast cancer by about 9%. In weighing the evidence, the 2007 global report from the World Cancer Research Fund and the American Institute for Cancer Research cited alcoholic drinks as a cause of breast cancer (see “Preventing cancer: Global report recommendations”). A possible explanation for the alcohol–breast cancer connection is that moderate alcohol consumption boosts the body’s levels of estrogen, which can promote breast cancer. Interestingly, having a diet rich in folic acid may cancel out this risk.

The Nurses’ Health Study and other studies have shown that women who consume more than one drink a day but also get 600 mcg or more of folic acid don’t have a higher risk of breast cancer than women who drink less. You can lower your risk of breast cancer by holding your alcohol intake to no more than one drink a day or less and getting 600 mcg of folic acid a day. You can get folic acid from a multivitamin, as well as from lentils and other legumes and fortified breakfast cereals, flour, pasta, rice, and other grain products. Most processed cold cereals are fortified with 100 mcg of folic acid, and most multivitamins provide 400 mcg.

Preventing cancer: Global report recommendations

In November 2007, the World Cancer Research Fund and the American Institute for Cancer Research released the second global report on Food, Nutrition, Physical Activity, and the Prevention of Cancer. For five years, a 21-scientist expert panel evaluated the best evidence conducted by dozens of scientists in 30 countries and then debated the meaning of the evidence to arrive at public health recommendations.

Many recommendations in the report also apply to dietary causes of cardiovascular disease. The notable exception is alcohol: for preventing cancers, the best level of consumption is zero; for cardiovascular disease, it may be one to two drinks a day. The authors also emphasize the importance of avoiding exposure to tobacco smoke.

Recommendations include the following:

Body fatness. Avoid weight gain and try to be as lean as possible without becoming underweight.

Physical activity. Be physically active for at least 30 minutes every day.

Avoid sugary drinks. Limit consumption of calorie-dense foods such as sodas and other high-calorie, low-nutrient foods.

Plant foods. Eat more of a variety of vegetables, fruits, whole grains, and legumes such as beans.

Animal foods. Limit consumption of red and processed meats.

Alcoholic drinks. If you drink, limit alcoholic beverages to no more than two drinks a day for men and one drink a day for women.

Salt. Limit your consumption of salty foods and foods processed with sodium.

Dietary supplements. Don’t rely on supplements to protect against cancer.

Special recommendation for breast-feeding women: Mothers should breast-feed exclusively for up to six months and then add other liquids and foods to their baby’s diet.

Special recommendation for cancer survivors: After treatment, cancer survivors should follow the recommendations for cancer prevention.

Source: Food, Nutrition, Physical Activity, and the Prevention of Cancer: A Global Perspective, World Cancer Research Fund and the American Institute for Cancer Research,, November 2007.

Controlling colorectal cancer

Your diet: Colorectal cancer

Good choices

  • Folic acid (folate), especially if you take it long term

  • Vitamin D

  • Exercise

  • Calcium, or low-fat and nonfat dairy foods

Risky choices

  • Red meat

  • Processed meats

  • Alcohol

  • Excess calories

Although many foods have been studied for their ability to raise or lower risk of colorectal cancer, at present, the only individual foods that appear to increase risk are red meat and alcohol. There is also some evidence that folic acid, vitamin D, and high-fiber foods may help reduce risk.

On the bright side, living an all-around healthy lifestyle may put you in good stead when it comes to preventing colorectal cancer. According to a prospective cohort study in BMJ in 2010 that followed 55,000 middle-aged cancer-free people for 10 years, almost one-quarter of colorectal cancers might have been prevented with adherence to five lifestyle recommendations: not smoking, daily physical activity for at least 30 minutes, avoiding heavy drinking, eating a healthy diet, and controlling waist size (less than 40 inches for men and 35 inches for women).

So while researchers continue to tease out the specific effects of individual food components discussed below, an overall healthy lifestyle may be your best bet.

Fiber. As with breast cancer, the list of foods scientists say may influence your risk of colorectal cancer continues to change. In particular, the evidence in favor of a high-fiber diet has gone up and down. For two decades, experts believed that fruits, vegetables, and especially high-fiber foods such as bran and whole-grain breads could help prevent colon cancer. Then several large studies, including the Nurses’ Health Study and others from Finland, Sweden, and the United States found fiber had no protective effect against this form of cancer. Since then, other studies have continued to weigh in.

In 2007, a study in The American Journal of Clinical Nutrition, which analyzed food questionnaires of nearly 300,000 men and 200,000 women, found that fiber intake wasn’t associated with a lower risk of colon cancer, though whole-grain consumption reduced the risk slightly. The study suggested that components in whole-grain foods other than fiber, such as minerals and B vitamins, may have a protective effect. More recently, a 2010 study in TheJournal of the National Cancer Institute, which analyzed the food diaries and questionnaires of 579 people who developed colorectal cancer and 1,996 people who didn’t, found that those who ate more fiber — an average of 24 grams daily — had a 30% lower risk of colon cancer than those who ate less fiber. Over all, eating whole grains and other fiber-containing foods may reduce your risk of colon cancer, though more studies need to be done to build the weight of the evidence.

Folic acid. Many studies have shown that more folic acid reduces the risk of colorectal polyps and cancer. For example, in Harvard’s Health Professionals Follow-up Study and the Nurses’ Health Study, men and women who took folic acid supplements for many years had a lower incidence of colon cancer than those who didn’t take them. These results have been corroborated by animal experiments with plausible biological mechanisms. Yet, the first large trial investigating the effects of folic acid supplementation showed no decrease and possibly some increase in colorectal adenomas and other cancers among men and women with a recent history of precancerous conditions.

Folic acid can be found in fortified breads and cereals and many fruits and vegetables, as well as in legumes such as lentils. Both the Harvard studies suggest that any benefit comes from folic acid specifically with supplement use, possibly because it is better absorbed in supplement form, although it is still readily absorbed from foods as well. The Healthy Eating Pyramid suggests taking a daily multivitamin containing folic acid.

Vitamin D. Vitamin D appears to protect against colon cancer in observational studies. An analysis of 16,618 participants in the National Health and Nutrition Examination Survey found a relationship between vitamin D status and colon cancer, but not total cancer. Again in 2010, researchers found a consistent link between higher vitamin D levels in the blood and a lower rate of colorectal cancer in an analysis of seven studies of colorectal cancer published in TheInternational Journal of Cancer.

Calcium/dairy foods. Many observational studies show that people whose diets are rich in calcium and dairy products tend to have a lower risk of colon cancer. A study in TheJournal of the National Cancer Institute, for example, which pooled preliminary data from 10 studies in five countries involving 534,536 participants, found that those who consumed the most milk had the lowest risk of colon cancer. Each additional 16 ounces of milk consumed daily was associated with a reduced risk of 12%.

Dietary fat. Findings have also rewritten the chapter on fat and colon cancer. Researchers originally associated a high-fat diet with higher risk of colorectal cancer because people who live in areas where high-fat diets are typical have a higher incidence of colorectal cancer than do people who live in areas with more moderate fat intake. But in more than a dozen studies involving thousands of volunteers, fat intake has borne no relation to people’s risk of getting colorectal cancer. Neither total fat intake nor the type of fat (saturated, trans fat, polyunsaturated, monounsaturated) has any influence.

Red meat. Several large studies show that people who eat a lot of red meat or processed meat or who drink more than a modest amount of alcohol have higher rates of colon cancer than people who consume lower amounts. Specifically, people who eat red meat, such as pork and beef, every day have a risk for colorectal cancer about two and a half times that of people who eat red meat less than once a month. Cementing already convincing evidence, a major American Cancer Society study published in JAMA in 2005 showed that people who ate the most red meat were 30% more likely to develop colon cancer than those who ate little or no red meat, and those who ate the most processed meat were 50% more likely to develop colon cancer.

How you cook your meat can make a difference. Cooking meat at high temperatures (by broiling, grilling, or searing) generates cancer-causing agents or carcinogens. These agents come in contact with the bowel wall during digestion, where they could potentially cause cancerous changes in the cells. Processing meats may also generate carcinogens.

Alcohol. Regular drinking of any type of alcohol appears to increase risk for colorectal cancer. Scientists think this happens because alcohol hampers the body’s ability to use the B vitamin known as folic acid or folate, and this nutrient plays a leading role in preventing colorectal cancer. There are two messages here. One is that if you’re going to drink, do so in moderation — no more than one drink a day for women and two for men. The other message is to get enough folate, but not too much — not more than 1,000 mcg per day.

Overeating. While you’re paying attention to the foods that you should and shouldn’t eat to prevent colon cancer, don’t overlook the big picture: the total amount of food you consume. So far, the strongest known dietary link to colon cancer is overeating — consuming more calories than you need and storing it as excess body fat. Overweight people are more likely to develop colon cancer than people whose weight is normal. Belly fat adds additional risk. One study cited in the global report found a 5% increased risk of colon cancer per inch of waist circumference.

If you need another reason to keep your middle whittled, consider: excess belly fat, especially around your waist, can significantly increase your risk of dying early, even if your BMI is normal (19 to 24), according to the Cancer Prevention Study II Nutrition Cohort in TheArchives of Internal Medicine in August 2010. The study found that men and women with the largest waists (47 and 43 inches or more, respectively) were at the greatest risk of dying prematurely from any cause.

Physical activity. No matter what your weight, you can reduce your risk of colon cancer further by exercising more. Physical activity may do more than burn excess calories. It also increases metabolic efficiency and speeds food through the gut.

Preventing prostate cancer

Your diet: Prostate cancer

Good choices

  • Soy

  • Selenium in food (uncertain)

  • Cooked tomatoes (uncertain)

Risky choices

  • Red meat

  • Calcium

The science of food and cancer prevention is a moving target that, so far, hasn’t produced clear-cut advice for prostate cancer prevention. Still, some interesting trends are emerging. A Western diet seems somehow to raise the risk for prostate cancer, but the details of exactly which foods are responsible are only beginning to become clear.

Calcium. A number of studies have linked an increased risk for prostate cancer with high calcium consumption. One of these is the Health Professionals Follow-up Study, which showed that men who consumed more than 2,000 mg of calcium a day had more than four times the risk of developing prostate cancer compared with those who consumed only 500 mg a day. A Swedish study also confirmed a higher rate of prostate cancer for men who consumed more calcium.

Researchers have separated calcium from the other components of dairy products, such as dairy fat, in order to determine whether it is the calcium or the dairy that is responsible for the increased rate of prostate cancer. However, in 2005, researchers analyzed 12 different studies that tracked men’s diets and rate of prostate cancer. They concluded, in their paper published in TheJournal of the National Cancer Institute, that both dairy products and calcium alone may be linked to slightly higher rates of prostate cancer.

This doesn’t mean men should eliminate calcium and dairy from their diets altogether. Men do need calcium as a crucial element in their diets. But get your calcium in the form of low-fat or nonfat dairy products, bolstered by other natural sources of calcium like salmon. Limit calcium to 1,000 to 1,500 mg a day. (One cup of low-fat yogurt contains about 380 mg of calcium; one cup of skim milk has 300 mg.) Avoid taking calcium supplements or taking too many calcium-rich antacids.

Other foods and nutrients. Thus far, selenium, found in certain plant foods, is showing some promise for protecting against prostate cancer. The amount of selenium in the soil, which varies by region, determines the amount found in the plant. But your selenium intake isn’t wholly dependent on the amount in the fruit and vegetables in your diet; animals that eat plants grown in selenium-rich regions also have higher levels. In the United States, the highest soil concentrations are found in the high plains of northern Nebraska and the Dakotas.

It’s best to get your selenium from food, however, because taking selenium supplements has not proved to help prevent prostate cancer, and too much may actually increase the risk. The Selenium and Vitamin E Cancer Trial (SELECT), which followed more than 35,000 men ages 50 and older, testing to see whether vitamin E or selenium supplements might affect prostate cancer risk, was stopped in 2008 after five years because the supplements, taken alone or together, didn’t prevent prostate cancer.

All in all, the evidence that any food or nutrient plays a significant role in preventing cancer of the prostate remains sketchy. Further study is clearly needed before scientists can reach any firm conclusions.

Beating bone loss

Your diet: Osteoporosis

Good choices

  • Vitamin D

  • Vitamin K

  • Calcium (women)

Risky choices

  • Heavy consumption of red meat

  • Excess vitamin A

Calcium is the one nutrient that comes to mind when most people think of preventing osteoporosis, a loss of bone mass that often increases with age and can lead to fractures (see Figure 3). Calcium is an important nutrient for building bone and for slowing the pace of bone loss that comes with age. But it’s not the single magic bullet for preventing osteoporosis, and some scientists suggest that too much calcium or dairy products may be unhealthy. Keep in mind that in addition to calcium, there are other nutrients and foods that help keep your bones strong — most importantly vitamin D, but also vitamin K and possibly fish.

Figure 3: Osteoporotic bone

Osteoporotic bone

As the illustration above reveals, osteoporotic bone is more porous and less dense than healthy bone. The result is bone that is fragile and more vulnerable to breaks. But strength training can slow bone loss and even help build bone.

How much calcium? The DRI for calcium is 1,000 mg a day for adults up through age 50 and 1,200 mg a day for people ages 51 and older, when bone loss accelerates. With age, the intestines absorb less calcium from the diet, and the kidneys seem to be less efficient at conserving calcium. As a result, your body uses more of the calcium stored in your bones for a variety of important metabolic functions.

Scientific studies have yielded different results regarding how much calcium you really need for preventing age-related bone loss. For example, a report in The American Journal of Clinical Nutrition in 2003 found that calcium intake during youth pays dividends many decades later. In this study of 3,215 women, those women over age 50 who, as children, drank very little milk (less than one serving a week) were twice as likely to fracture a hip as women who had consumed more than one serving a day. But calcium intake during adulthood may not have the same benefit. Seven studies done in the United States and Europe that have followed thousands of people for many years have found no correlation between a high intake of calcium in adulthood and fewer bone fractures. For example, in the Nurses’ Health Study and the Health Professionals Follow-up Study, people who drank two or more glasses of milk a day were no less likely to break a hip or forearm than people who drank one glass or less a week.

Because preliminary findings suggest that high calcium intake may increase the risk of prostate cancer (see “Preventing prostate cancer”), men should avoid taking calcium supplements or taking too many calcium-rich antacids.

Vitamin D. In building bone, calcium has an indispensable assistant: vitamin D. This vitamin helps the body absorb calcium, and some researchers think that increasing vitamin D can help prevent osteoporosis. Milk sold in the United States is fortified with vitamin D. Vitamin D is also prevalent in fortified breakfast cereals, eggs, and vitamin supplements. Other dairy products made from milk, such as cheese, yogurt, and ice cream, aren’t typically fortified with vitamin D and contain only small amounts. However, some brands of yogurt are fortified with it, as well as some juices. If possible, a small amount of sun exposure can help your body manufacture its own vitamin D — about five to 30 minutes of sunlight between 10 a.m. and 3 p.m. twice a week to your face, arms, legs, or back without sunscreen will enable you to make enough of the vitamin. People with fair skin that burns easily should protect themselves from skin cancer by limiting sun exposure to 10 minutes or less. Food and sun exposure should suffice, but if not, some experts advise getting 1,000 IU of vitamin D daily from a supplement.

Vitamin K. The Nurses’ Health Study found that women who got more than 109 mcg of vitamin K a day were 30% less likely to break a hip than women who got less. To get enough vitamin K, eat one or more servings daily of dark green lettuce, broccoli, spinach, Brussels sprouts, or kale. Vitamin K helps regulate calcium and build bone.

Vitamin A. Eating too much vitamin A can increase your risk of osteoporosis. Scientists have known for years that megadoses of vitamin A can deplete bone by interfering with the ability of vitamin D to maintain sufficient calcium levels. Then in 2002, Harvard researchers involved with the Nurses’ Health Study reported that vitamin A may promote bone loss even at levels considered safe. In the study, postmenopausal women who ingested 3,000 mcg or more per day of vitamin A from food, supplements, or both over an 18-year period were more than twice as likely to fracture a hip as women who had less than 1,500 mcg daily.

The DRI for vitamin A is 700 mcg for women, with levels up to 3,000 mcg considered safe. The Nurses’ Health Study suggests that postmenopausal women are best off with a vitamin A intake in the lower half of this range. To make sure your intake is at the right level, read the labels of the foods you often eat to see how much vitamin A they contain, paying special attention to fortified breakfast cereals. If you take a multivitamin, see how much vitamin A it has. If your multivitamin contains more than the DRI, consider switching to a brand with a lower amount. However, beta carotene, often used in multivitamins as a source of vitamin A, doesn’t pose this risk.

Banishing birth defects

Your diet: Birth defects

Good choices

  • Folic acid (folate)

  • Dark green leafy vegetables

  • Fortified breads and cereals

Risky choices

  • Alcohol

  • Many drugs and medications

Decades ago, researchers found that women with poor diets were most likely to give birth to babies with neural tube defects. Subsequent studies traced the problem specifically to a lack of folic acid, a B vitamin. In 1992, the RDA for folic acid was increased to 400 mcg, and the newer DRIs call for that amount as well.

Because it was hard to get that much folic acid naturally from food, the FDA requires that certain foods — breads, flours, pastas, rice, and other grains — be fortified with folic acid. Taking a multivitamin containing the standard 400 mcg is important for all women of childbearing age. Research suggests that the daily dose for women of childbearing age should be even higher, as much as 800 mcg. But with so many foods now fortified, most people get plenty of folic acid.

Eradicating eye disease

Your diet: Eye disease

Good choices

  • Dark green leafy vegetables

  • Supplements for people at risk of developing advanced stages of wet AMD:

    • Vitamin C: 500 mg daily

    • Vitamin E: 400 IU daily

    • Beta carotene: 15 mg daily

    • Zinc: 80 mg daily

    • Copper: 2 mg daily (copper is necessary because high levels of zinc may cause copper deficiency)

Risky choices

  • High-glycemic foods such as cakes, cookies, and white bread

  • Saturated fat

Age-related macular degeneration (AMD), the leading cause of blindness in seniors, is a condition in which the center of the retina at the back of the eye, called the macula, deteriorates.

Your diet may play a role in increasing your risk of developing AMD. Studies have found that AMD is more common in people whose diets are deficient in several nutrients. These include the antioxidant vitamins C and E; the mineral zinc, which exists in trace amounts in the body but is concentrated in the eye; and lutein and zeaxanthin, substances known as carotenoids that are found in green vegetables and fruits and are also the dominant pigments in the macula. A diet high in refined carbohydrates and sugary foods such as cakes, cookies, and non-whole-grain bread may also raise your AMD risk. People whose diets contained more of these high-glycemic foods were more likely to develop AMD than those who ate fewer of those foods, according to a 2007 study in The American Journal of Clinical Nutrition. Some evidence hints that a diet high in saturated fat may increase your risk of developing AMD, too. Middle-aged and older people may benefit from diets rich in fresh fruits and dark green leafy vegetables such as spinach or collard greens.

The large, multicenter Age-Related Eye Disease Study (AREDS) reported in 2001 that for people at high risk of developing an advanced form of the disease known as wet AMD, taking a high-dose combination of vitamins C and E, beta carotene, and zinc lowered risk by about 25%. The supplements provided no apparent benefit for participants who had either no AMD or early AMD. But ask your doctor about taking such supplements if you have intermediate dry AMD in one or both eyes, or advanced dry or wet AMD.

Discouraging diverticular disease

Your diet: Diverticular disease

Good choices

  • High-fiber foods

  • Plenty of fluids

Risky choices

  • Low-fiber diet

You probably know that fiber helps prevent constipation, but it has other benefits for the digestive tract, too. Fiber from cereals, fruits, and vegetables helps prevent diverticular disease, an umbrella term for two diseases of the colon: diverticulosis and diverticulitis.

Diverticulosis, a condition in which balloon-like pouches (diverticula) develop in the colon wall, is one of the most common afflictions of the colon, affecting about 10% of Americans and up to half of those over age 60. Although diverticulosis usually causes few or no symptoms, it can develop into diverticulitis, a painful inflammation or infection caused when a seed or a piece of stool becomes trapped in one of the diverticula. Symptoms of diverticulitis are sudden, intense abdominal pain and sometimes fever, nausea, constipation, or diarrhea. Diverticulitis can cause the bowel to rupture, spilling its contents into the abdominal cavity, which can be fatal.

Epidemiologists think that a low-fiber diet sets the stage for diverticula to form in the colon. A diet with plenty of fiber can keep stools soft and bulky and prevent undue pressure. If you increase your fiber intake, make sure to get plenty of fluids, to help the fiber pass through your system.

An emerging idea among researchers is that lack of fiber alters the intestinal bacterial flora, a change that may allow a low-grade chronic inflammation in the intestinal lining. More study is needed to confirm this hypothesis.

Arresting Alzheimer’s disease

Your diet: Alzheimer’s disease

Good choices

  • Fruits and vegetables

  • Plant oils

  • Whole grains

  • Moderate alcohol intake

Risky choices

  • Saturated and trans fats

Several studies suggest that a Mediterranean diet (see “Eating plans for good health”) high in plant foods and plant oils reduces the risk of developing Alzheimer’s disease in European and North American populations. In addition, a study published in 2007 in Neurology shows eating a Mediterranean diet may even help people with the disease live longer.

Some epidemiologic studies suggest that higher dietary intakes of antioxidants, vitamin B6, vitamin B12, folate, unsaturated fats, and fish are related to a lower risk of Alzheimer’s. There is some evidence that elevated levels of homocysteine (a component in the blood linked to cardiovascular diseases and low levels of vitamin B12) may increase the risk for dementia, including Alzheimer’s disease. But further research is needed.

Other studies have explored the relationship between fish consumption, omega-3 fatty acids, and Alzheimer’s disease. All told, the results have been inconsistent.

However, moderate alcohol intake, particularly wine, may be related to a lower risk of Alzheimer’s. Over all, aside from eating a general healthy diet, the existing evidence doesn’t support recommending specific supplements, foods, or diets to prevent Alzheimer’s disease.

Aside from being nutritious, healthy foods must also be safe — untainted by bacteria, free from dangerous levels of pesticides and other impurities. Concerns about food safety have grown stronger and more far-reaching. Headlines warn of contamination in beef, eggs, lettuce, and other fruits and vegetables. Fears of toxic pesticides and potential problems from genetically engineered foods are widespread.

Modern farming and food processing methods have done a great job of making more food available more cheaply. But these methods have created safety issues. Efforts to maximize yield have led to greater use of pesticides on crops and hormones in animals. The crowded animal pens of factory farms and the large-scale assembly-line nature of slaughterhouses and food processing plants have increased the spread of dangerous bacteria in food. Farmers’ routine addition of antibiotics to animal feed has given rise to bacteria that are resistant to treatment with medications.

In truth, our food supply is reasonably safe, but it could be safer. The government is working with farmers and slaughterhouses to take greater precautions against the spread of germs. Organic and sustainable agriculture and other strategies can help reduce the need for synthetic fertilizers and toxic pesticides, but drive up the cost. Meanwhile, there are steps you can take in selecting, handling, and storing food to minimize safety problems.

The biggest threat: Contamination

The food safety threat that eclipses all others is bacterial contamination — a problem that mainly affects meat, fish, and dairy products, and also some fresh produce. Microbes that not long ago were either unheard of or considered a minor threat now cause 76 million cases of food poisoning and 5,000 deaths in the United States each year. The main reason that food contamination is on the rise is that large-scale processing and packaging involves larger batches of food. So when contamination does occur, it affects larger amounts of food than ever before — which is shipped to more supermarkets, restaurants, and school cafeterias.

The widespread use of antibiotics in animal feed is another factor because it promotes the emergence of disease-resistant pathogens that are resistant to antibiotics. These resistant germs breed inside the animals and are then passed to humans in meat, eggs, and other foods.

Meat, poultry, eggs or foods made with raw eggs, raw shellfish, cold cooked seafood such as smoked salmon, soft cheeses, and bean sprouts are most prone to contamination. You can help guard against food poisoning by washing meat and produce before handling it, cooking foods thoroughly, and refrigerating them (see “Handling food safely”). But these measures aren’t foolproof, because contamination can spread during delivery to other foods that aren’t normally affected. Fruits, vegetables, and milk have become tainted after being shipped in the same trucks as contaminated eggs or meat.

To help prevent such foods from even reaching delivery trucks, the USDA, since 1995, has been phasing in a more comprehensive, scientific system of inspecting meat, poultry, and processed egg products. This surveillance system targets the most prevalent sources of food-borne illness: Escherichia coli (E. coli) in ground meat, and Salmonella in ground meat, poultry, and eggs. Slaughterhouses must regularly test meats for the presence of E. coli, and government inspectors must test for Salmonella.

With these challenges in mind, you can play your part by becoming aware of the nature of food safety problems and taking steps to ensure your own safety when handling and cooking foods. Common sources of contamination include the following:

E. coli. A toxic variation of this bacterium, found mainly in ground beef, causes an estimated 25,000 cases of food poisoning in the United States each year and kills about 100 people. It’s the most common cause of sudden kidney failure in children and can also cause kidney damage in adults. Contamination occurs during meat processing, when E. coli from the animals’ intestines becomes mixed in with the meat. E. coli contamination has prompted massive recalls of millions of pounds of ground meat. The damage is done by a toxin known as shiga, which is commonly found in the O157:H7 subtype.

Salmonella. This bacterium is found mostly in meat and eggs. But it spreads to other foods, such as ice cream, vegetables, and fruit, when they’re shipped with contaminated meat or eggs. A study in The New England Journal of Medicine in 2001 showed how alarmingly prevalent it is: 20% of 200 samples of ground chicken, beef, turkey, and pork contained Salmonella. Of particular concern, 84% of the Salmonella samples were resistant to at least one antibiotic, and 53% to at least three antibiotics. This means that when animals carry Salmonella — and when people get Salmonella food poisoning — it’s more difficult to cure than it was in years past.

Campylobacter. Usually transmitted by poultry, this bacterium is the most common cause of bacterial gastroenteritis in the United States, causing approximately 2.5 million cases of diarrhea, fever, and abdominal cramps each year. Antibiotic-resistant strains are becoming more prevalent because of the widespread use of antibiotics in chicken feed. In 2007, the CDC reported increasing resistance to ciprofloxacin, a fluoroquinolone, the most common antimicrobial drug prescribed for Campylobacter infections in people. To help control this problem, the FDA has begun to reduce the use of fluoroquinolones in poultry. One, enrofloxacin, is now prohibited in poultry.

Handling food safely

You can prevent most cases of food poisoning in your household by preparing and storing your foods safely. These precautions will help kill germs that are present in the meat and eggs you buy and help you avoid introducing new bugs to your food at home.

Rinse foods. Rinsing can wash off some germs from meat, poultry, and fish and pesticide residues from produce. Rinse all meat, poultry, and fish under running water before cooking. Rinse all fruits and vegetables under running water before cooking or serving them.

Wash your hands. Frequent handwashing helps prevent you from passing germs from one food to another. Use soap and water to wash your hands each time you handle a raw food. Don’t wipe your hands on a dishtowel without washing them first.

Use separate utensils. Don’t prepare meat and fish on the same surface that you use for other foods — otherwise, you risk contaminating those foods with bacteria from the meat and fish. Use one cutting board for meats and fish and a second one for produce. Be sure to wash the cutting boards with soap and water after each use. Use different knives to cut different foods to prevent cross-contamination.

Cooking. Cook all meat, poultry, eggs, and freshwater fish. Don’t rely on color alone to indicate whether meat is fully cooked. The USDA recommends that everyone use a meat thermometer. Different temperatures are required to kill off germs in different kinds of meat. It’s also important to cook hot dogs and other precooked meats and fish, to destroy bacteria that may have contaminated them in the processing plants.

Storing. Don’t leave any foods, before or after cooking, at room temperature for more than two hours (one hour if the air temperature is above 90° F). Put them in the refrigerator or freezer. The temperature inside your refrigerator should be 40° F or below; your freezer should be at 0° F or below. If you have large amounts of leftovers, divide them into small batches when you put them away in the refrigerator or freezer. That way, the temperature of each batch will reach a safe level faster. Keep in mind that freezing does not necessarily kill bacteria; wash meats and poultry thoroughly after thawing, and handle them the same as you would fresh meats (see Table 6).

Table 6: How long to store foods

Discard foods after the given time period has elapsed.




Fresh meat and fish

Ground beef

1–2 days

3–4 months

Steaks and roasts

3–5 days

6–12 months

Pork chops

3–5 days

4–6 months

Ground pork

1–2 days

3–4 months

Pork roasts

3–5 days

4–6 months

Lean fish (flounder, haddock, cod, etc.)

1–2 days

up to 6 months

Fatty fish (blue fish, perch, salmon, etc.)

1–2 days

2–3 months

Whole chicken

1–2 days

12 months

Chicken parts

1–2 days

9 months


1–2 days

3–4 months

Cured meats

Lunch meats (ham, turkey, etc.)

3–5 days

1–2 months


1–2 days

1–2 months

Dairy products


5 days

1 month


3–4 weeks

2–4 months

Ice cream, ice milk

2–4 months

Uncooked eggs (in shell)

3 weeks

Hard-boiled eggs

1 week

Source: FDA.

What about pesticides?

Residues of pesticides used to kill insects, weeds, and fungi on farms are present in many of the fruits and vegetables on the market. In some tests, about half of fruits and vegetables had residues. The Environmental Protection Agency (EPA) rates many of these pesticides as known or probable carcinogens. Evidence also suggests that pesticides can cause other health problems, such as impaired immune function and low sperm count.

No one knows how serious a threat pesticides pose to the average consumer. Estimates are extrapolated from the incidence of illnesses among farm workers and from research on animals. But a report by the National Academy of Sciences in 1993 concluded that infants and children are more vulnerable than adults to pesticide hazards because they are smaller and because they eat much larger amounts of certain fruits, such as apples in apple juice. As a result of that study, Congress passed the Food Quality Protection Act in 1997, which requires all pesticide exposures to be proved safe for infants and children.

Following are some steps you can take to reduce your exposure to pesticides.

Buy locally grown produce in season. Produce grown on small, nearby farms is less likely to be treated with pesticide waxes used to inhibit fungus growth on produce that’s shipped long distances. Locally grown fruits and vegetables are available only in season.

Wash fruits and vegetables, and peel them when possible. One study found that washing produce with a mix of water and mild dishwashing detergent, peeling the skins, and (for lettuce and cabbage) removing the outer leaves eliminated pesticide residues in 21% of fruits and vegetables. Peeling alone eliminated all of the residues in bananas, carrots, and potatoes. Similarly, corn had no residues after it was shucked.

Is “organic” or “natural” better than other foods?

You may wonder whether organic produce is a healthier choice. To be labeled “organic,” produce must meet the guidelines in a 2002 federal law. These guidelines state that no synthetic chemicals can be used to grow the produce or to treat it after harvesting. USDA agents certify which produce can be called organic and can impose penalties of up to $10,000 for violations. Organic farming leaves fewer pesticide residues than conventional farming, which certainly makes it healthier for the environment and possibly healthier for you. Keep in mind, however, that even organic produce isn’t completely free of synthetic pesticide residues because these chemicals can persist in the soil for decades.

As defined by the USDA, organic foods are those grown only without the use of most conventional pesticides, petroleum- or sewage-based fertilizers, genetic engineering, or ionizing radiation. Organic farmers can use manure-based fertilizers if they comply with very specific regulations. For meats, eggs, and dairy products to be called organic, the farmers can’t give the animals antibiotics or growth hormones. Livestock must eat organic feed that doesn’t contain parts of other slaughtered animals, and the livestock must be allowed outdoors. To be labeled organic, a food also can’t be produced with the use of genetic engineering or irradiation (see “Food irradiation” and “Genetic engineering”).

Organic and “natural” aren’t synonymous. Products labeled “natural” contain no artificial ingredients or added colorings or they’re only minimally processed, meaning the raw product hasn’t been fundamentally altered. The label must explain the use of the term “natural,” as in no added colorings or minimally processed. Although there may be some organic foods that are also natural, a product labeled “natural” isn’t organic unless it meets the federally regulated definition of organic.

Organic foods don’t generally look different from their non-organic counterparts. Look for the USDA organic seal or the word “organic” on the label to make sure. Foods must be at least 95% organic to bear the USDA organic seal. Multi-ingredient foods (such as cereal or soup) that are 70% to 95% organic can’t display the seal, but they can use the word organic to describe up to three ingredients on the front of the packaging. Foods that are less than 70% organic can identify specific ingredients as organic in the ingredient list.

Although all foods that have the USDA seal are certified organic foods, the reverse is not true: all organic foods do not necessarily carry the USDA label, because applying for the labeling is voluntary. Foods that are truly organic might not have the seal or even use the word organic on the label.

But the labels don’t answer another nagging question: how important is it to buy organic? According to its Web site, the USDA “makes no claims that organic food is safer or more nutritious than conventionally produced foods.” Harvard nutrition experts say there is no solid evidence that organic foods in general are healthier for humans, but that organically raised meat may prevent the spread of diseases such as bovine spongiform encephalopathy, better known as mad cow disease. Conventionally raised livestock can catch this disease by eating the meat or bones of infected animals. But because animals sold as organic meat do not eat slaughtered animals, they are unlikely to catch mad cow disease.

What about the health value of organic produce? A 2002 study showed that children who ate organic fruits and vegetables had significantly less pesticide in their urine than those who followed conventional diets. This means that when children ate conventionally grown foods, pesticides entered their blood and circulated through their bodies before being excreted. But neither this study nor any others to date prove that organic foods are healthier, because the level of pesticides found hasn’t been definitely linked to any health risk.

Additives and your health

Additives are substances added to manufactured foods. This umbrella covers a broad range of substances: vitamins and minerals that fortify a food, preservatives that help keep a food from spoiling, sugar and other food flavorings (natural and artificial), and dyes added to make a food look appetizing.

Some additives are good for you, notably vitamins and minerals. But you may wonder about the safety of other additives, especially those with names that sound more at home in chemistry class than on your plate. Under federal law, most additives must be proved safe before a food manufacturer can put them into food. The exceptions are those that have been used for a long time withno apparent problems. These older additives range from sugar and salt to potassium nitrite, a preservative used in hot dogs and luncheon meats.

Some additives are a cause for concern. Sodium nitrate and sodium nitrite in hot dogs, luncheon meats, and smoked fish may create small amounts of cancer-causing chemicals called nitrosamines during cooking. Research on animals suggests that other additives may cause cancer. These include five artificial food colorings (blues #1 and #2, green #3, red #3, and yellow #6), two artificial sweeteners (saccharine and acesulfame K, or acesulfame potassium), and potassium bromate in white flour products.

Other additives may cause allergic or other adverse reactions. Monosodium glutamate (MSG), a flavor enhancer, can cause headache, nausea, and difficulty breathing in some people. Cochineal and carmine, which are artificial colorings made from pulverized insects, have caused a range of allergic reactions, from hives to anaphylactic shock.

Although other additives appear safe, the presence of a long list of food additives in the ingredients of any packaged food is a red flag — you’re better off choosing a food with fewer additives to reduce the health risk.

Other food safety issues

As farming and food production methods change, new safety issues arise. For instance, modern factory farming methods are largely responsible for the spread of mad cow disease. Some technological advances on the horizon or already in limited use have great potential to combat food-borne contamination and reduce our reliance on toxic pesticides. But some observers suggest that these innovations may pose new risks to our health and environment. Following are some of the most important emerging food safety issues.

Food irradiation

An overwhelming body of scientific evidence has shown food irradiation to be a safe and effective method of destroying bacteria and parasites in foods. Different food irradiation technologies exist, but they all use a beam of energy — usually either electrons or x-rays — that can penetrate the surface of a food and kill off germs in its path. The electron beam machine is similar to the machine hospitals use to sterilize medical equipment. The irradiating x-ray machine is a stronger version of the x-ray machine in dentists’ offices. Irradiation can help eliminate E. coli, Salmonella, Campylobacter, and other common causes of food contamination.

Studies show that irradiated foods are safe. Food doesn’t become radioactive or develop dangerous substances, and its nutritional value isn’t significantly changed. The safety of the technology has been endorsed by the World Health Organization and the CDC. The FDA has approved food irradiation for a variety of foods including meats, eggs, seeds, shellfish, and some fruits and vegetables. Foods that are exposed to radiation must be identified with an international symbol called a radura.

In the future, food irradiation could become as routine as milk pasteurization. Like pasteurized milk, irradiated foods still must be handled and stored safely; otherwise, they can become contaminated before they reach your table.

Genetic engineering

Genetically modified organisms (GMOs) are foods that result from a process of moving genes across natural boundaries from one plant or animal to another in order to confer certain traits. There are several ways of altering genes in plants and animals. Traditional breeding methods continue to be an effective and widespread means of enhancing the nutritional content of food.

Most GM products on the market have been engineered for agronomic traits, such as pest resistance or herbicide resistance, rather than for consumer health benefits.

Are genetically engineered foods safe? The National Academy of Sciences, in its 2004 report Safety of Genetically Engineered Foods, concluded that while genetic engineering of foods isn’t inherently dangerous, it may produce unintended changes in the composition of foods. The report recommends that genetically engineered foods be evaluated on a case-by-case basis and calls for ongoing monitoring of the population for adverse health effects. There’s no well-designed, long-term safety testing, which is truly what is needed to ensure safety.

A study in TheInternational Journal of Biological Sciences highlights this concern. The authors found an association in rats between consumption of GM corn for just 90 days and organ failure. The American Academy of Environmental Medicine (AAEM) has also taken an aggressive position against GMOs. It states that they “pose a serious health risk in the areas of toxicology, allergy and immune function, reproductive health, and metabolic, physiologic and genetic health and are without benefit.” The AAEM recommends that people avoid GMs that are labeled, and that studies be done to establish their long-term safety.

That said, genetically engineered foods are already widespread. If you worry about eating genetically engineered foods, keep in mind that in most cases, you won’t be eating the genes themselves, because by the time the food is processed — from corn to corn syrup, for example, or from soybean to soybean oil — none of the genes or proteins are left.

Some people are rightly concerned that an allergen might be transferred from one food to another during the genetic engineering process. This has already happened in the case of an allergen from Brazil nuts being inadvertently transferred into soybean plants. That’s why the government requires manufacturers to test their genetically engineered foods for allergens.

Many GMs are safe, but if you want to be especially cautious, you can avoid GMOs, buy organic, look for terms on the label such as “non-GMO” or “Made without genetically modified ingredients,” and choose 100% grass-fed beef. Most cattle are raised eating GMO feed. But choosing 100% grass-fed beef ensures that you’re not indirectly consuming GMOs from the meat you eat.

Learning which foods are healthy is half the challenge. The other half is knowing how to shop for them. The main rule of thumb is to choose a variety of whole, unprocessed foods to ensure that you get adequate amounts of nutrients and disease-fighting substances. But even savvy shoppers can get confused wading through all the choices at the market, decoding food labels, and cutting through the marketing claims on food packages. Here is a simple, no-nonsense guide to separating truths from half-truths, as well as determining which fruits, vegetables, meats, and fish are freshest and healthiest.

Reading a food label

If you aren’t in the habit of reading food labels, try it. You will be surprised to see how much great information appears on this small government-mandated label. Federal law requires all packaged foods to bear a label stating the ingredients, the serving size, calories, total fat, saturated fat, trans fat, total carbohydrates, protein, cholesterol, sodium, and Daily Values (DV) of certain nutrients, such as vitamin A, vitamin C, calcium, and iron.

You can use this food label in many ways. Look at the portion size first, since all the numbers that follow are relative to it. What looks like a single serving to you may be divided into two portions on the label to make the calories, fat, or sodium appear to be low.

Use the nutrients list to compare the amount of fiber among different brands of cereals, or check whether your bread is fortified with folic acid or your orange juice is fortified with calcium. If you see that there are 12 grams of fat and that 10 of them are saturated or trans fat, you’ll know it’s not a healthy choice for lowering your risk for heart disease, diabetes, or hypertension.

Other elements of the food label can provide useful information as well. Here are some examples.

Ingredients list. The ingredients are listed by weight from the largest to the smallest amounts. The healthiest products have the healthiest ingredients. Seeing sugar, corn syrup, salt, or some other unhealthy ingredient high on the list is a red flag. Sometimes food manufacturers use several different kinds of sugar — such as corn syrup, malt syrup, or fructose — listed separately, so that “sugar” doesn’t appear first on the list; this is a tip-off for high sugar content.

Product dates. Perishable foods such as meats, poultry, fish, dairy products, and baked goods are marked with dates that say “use by,” “sell by,” or “best if used by.” The federal government doesn’t require dating on foods except for infant formula and certain baby foods. But more than 20 states require date labeling of some foods, and many manufacturers use them regardless. The most useful date is the “sell by” date. This tells the store how long to keep the product on the shelf. Don’t buy any food after this date. The other dates tell you how long a product will taste its best or be at peak quality, but they don’t tell you when it will spoil (see Table 6).

Low calorie, reduced calorie. A “low-calorie” food may have no more than 40 calories per serving. A “reduced-calorie” food has no more than two-thirds the calories that are in the regular version of the product.

Light, lean. These terms appear on all sorts of packaged foods, from potato chips to soy sauce, to suggest that they’re healthier than the original versions. But government regulations state that the term “light” has a quantifiable meaning only when used to refer to the fat, calories, or sodium in a food. It means that a food contains no more than three-quarters the fat, two-thirds the calories, or half the sodium of the original.

Free. A product with this label has none or negligible amounts of one of these components: fat, saturated fat, cholesterol, sodium, sugar, or calories.

Choosing meat and fish

Look for the leanest cuts of beef, poultry, and other meats, because they have the least saturated fat. For beef, the leanest cuts are round, loin, and sirloin. Ground beef is higher in fat than these cuts; if you’re cooking hamburger or meatballs, buy “extra-lean ground beef,” which has roughly 10% fat (compared with 20% or 25% in other ground meat). The leanest cut of chicken and turkey is the breast (white meat); of pork, the tenderloin. The leanest cuts of lamb are the leg, loin roast, and chops.

In addition, the healthiest meats come from “free-range” animals raised without antibiotics in their feed. Free-range cattle are less likely to develop infections (and need antibiotic treatment) than animals raised factory-style in tight pens.

High-quality fish can be fresh or frozen within hours of being harvested. On whole fish, the scales should be intact and colorful — color fades along with freshness. The eyes should be bright and the gills red and without slime. When buying fresh fillets, examine the flesh. It should be moist and elastic and not brown or dry at the edges. Frozen seafood should have solid flesh, no discoloration, and little or no odor.

Grading meat

Traditionally, labels on beef and poultry indicated only their grade, or quality. Starting in 2012, most grades of meat will be required to display a “Nutrition Facts Label” similar to that which appears on other packaged foods. The following “grading” system still applies.


Beef or lamb cuts with the most marbling, or fat.


Beef or lamb cuts with less marbling than prime.


Lean cuts of beef.

Grade A

The highest quality poultry, the grade usually sold in retail markets. It has no defects such as bruises or broken bones. Lower grades of poultry are used in processed meat products. If you see poultry in your supermarket that’s not graded, it’s not Grade A.

Buying grains and beans

Look for “whole wheat” or another whole grain as the first ingredient in bread and rolls. In addition, consider whole-wheat pasta, which has a lower glycemic index than white pasta. Similarly, brown rice has a lower glycemic index than white rice. For variety, try some healthy alternatives to these grains, such as bulgur or quinoa.

Lentils, chickpeas, kidney beans, peanuts, and other legumes are important sources of vegetable protein. They come either dried or canned. Dried beans have a slight edge over canned beans because they’re unprocessed, have no added salt, and are inexpensive. But they typically must be soaked in advance or boiled for up to an hour and a half, though lentils take only 30 minutes and split peas can be cooked in as little as 15 minutes. One trick is to prepare a lot of beans at once, then freeze them in batches, to thaw and reheat later. Canned beans are an option when you’re pressed for time because they’re already cooked. Look for reduced-salt versions and always drain and rinse before using.

Shopping for fruits and vegetables

Most Americans don’t meet the minimum U.S. government advice of five servings a day of fruit and vegetables, let alone the preferred nine to 11 servings a day recommended by many health experts. One-third of our daily vegetables come from just two sources: iceberg lettuce and potatoes, according to the USDA, and most potatoes are eaten in the form of French fries. Americans do a little better with fruit, eating mostly apples, oranges, or bananas.

The healthiest fruits and vegetables are picked fresh and consumed shortly after that. The longer they’re stored, the less nutritional value (and taste). Buy locally grown, seasonal produce when you can (strawberries in the spring, zucchini in late summer). They’re more likely than out-of-season produce to have been grown locally (or at least domestically) and not stored for long periods. Also consider buying organic produce because it has lower levels of pesticide residues than other produce.

Keep in mind that frozen fruits and vegetables are almost as tasty and nutritious as fresh-picked ones, and they may be even better for you than out-of-season fresh produce that was picked unripe, stored for weeks, then shipped across the country or the globe.

Select a variety of fruits and vegetables, concentrating on the most deeply colored ones because they contain substances that have healthful effects (see “Fruits and vegetables”). Have a spinach salad instead of iceberg lettuce, for example. Eat sweet potatoes instead of white potatoes.

You can tell a lot about the condition of fruits and vegetables by looking at them and feeling them. Greens shouldn’t be wilted. Carrots should be crisp, not limp. Peaches, nectarines, and cantaloupes should be slightly soft, but not mushy. Brown spots on fruits and vegetables are signs of spoiling. On the other hand, produce that’s too perfect-looking isn’t always desirable. Shiny, flawless skin on apples, peppers, and cucumbers is a sign that they’ve been coated in a pesticide wax. Although the wax can be washed off with soap and water, you’re better off avoiding it entirely.

Browsing the dairy case

Because regular milk, cheese, and other milk products contain saturated fat, look for nonfat or low-fat versions. Nonfat milk has just 1 gram of fat per cup, compared with 8 grams in whole milk. Low-fat (1%) milk has 2 grams of fat per cup.

The yogurts with the least fat are made with skim or low-fat milk instead of whole milk or cream. Be aware that most cheese has a lot of fat even if it’s labeled “low-fat.” Although a half-cup of low-fat cottage cheese has just 1 gram of fat, low-fat ricotta cheese has a whopping 10 grams of fat per half-cup.

When choosing frozen desserts like ice cream, be aware that the gourmet or premium brands often have more unhealthy saturated fat. A half-cup of gourmet ice cream has 12 grams of fat because it’s made with cream. Compare that to the low-fat products or frozen yogurt with 3 grams. Even better, try sherbet with only 2 grams, or sorbet with none. Remember that even sorbet and frozen yogurt are laden with added sugars; they’re not health foods by any stretch of the imagination.

For safety’s sake, always be sure to buy milk and milk products that are pasteurized. Pasteurization uses heat to kill off germs during processing. Don’t imagine that unpasteurized products are healthier or purer. Pasteurization has significantly reduced the incidence of diseases transmitted by milk. Another way to guard against contamination is to buy milk and other dairy products (including eggs) before the “sell by” date.

Eating out

In general, restaurant food isn’t as healthy as what you prepare at home. For one thing, most chefs use lots of butter and salt. And, while some high-end restaurants serve tiny portions of artistically arranged food, most American restaurants overdo portion sizes. But if you’re smart about what you order, you can get a healthy meal — including dessert — when eating out. Here are some guidelines.

Check the restaurant’s Web site. Many fast-food restaurant sites list nutrition information. You might be surprised by how some items compare to others in terms of nutrients, especially fat, calories, and sodium. You can also scope out a restaurant’s menu ahead of time at Web sites such as In general, menus don’t tell you very much about an item’s nutritional value, but they can give you a general idea of which dishes are served with vegetables, for example.

Ask about fried foods. Frying foods usually adds more fat to a food than broiling, baking, or sautéing, so the calorie count is likely to be high. Many restaurants have switched away from frying foods in trans fat and saturated fat and are using healthier fats such as unhydrogenated vegetable oils. Ask your server what kind of oil is used for frying.

Ask for extra vegetables. Many restaurant entrées don’t come with a generous serving of vegetables. But you can easily remedy that by ordering vegetables from the side dish selection or asking for more.

Avoid dishes prepared with gravy and heavy sauces. Or ask for your dish to be prepared with half the sauce or sauce on the side. Because gravy is often made with fatty pan drippings from meat, it’s relatively high in saturated fat. Many sauces are made with cream, which is also high in saturated fat.

Ask the waiter how large the entrées are. If they’re bigger than the meals you usually eat, consider ordering an appetizer instead or sharing an entrée with someone else. And you don’t have to eat everything on your plate. Take home your leftovers for tomorrow’s lunch.

Eat a light, healthy snack such as a piece of fruit or some carrots before going out. That way, you won’t be so ravenous when you arrive at the restaurant that you’ll gorge on the bread served at the table.

Share desserts. If you want a sweet dessert, consider sharing it with others at your table. You’ll get the full taste, but just a fraction of the calories, sugar, and bad fats. Or look for lighter desserts such as sorbet or fruit.


American Dietetic Association
120 S. Riverside Plaza, Suite 2000
Chicago, IL 60606

This large organization of food and nutrition professionals provides information and advice to the general public through its Web site, outreach efforts, and publications.

The Nutrition Source — Knowledge for Healthy Eating
Harvard School of Public Health
Department of Nutrition

This Web site gives free public access to the latest information on nutrition and health.

Books and publications

Eat, Drink, and Weigh Less: A Flexible and Delicious Way to Shrink Your Waist Without Going Hungry
Mollie Katzen and Walter C. Willett, M.D.
(Hyperion, 2007)

This book teams Mollie Katzen, author of the landmark Moosewood Cookbook, with Dr. Walter Willett, head of the Harvard School of Public Health’s Department of Nutrition. Together they’ve created a weight-loss plan that’s easy to implement and filled with delicious foods and more than 100 delicious recipes.

Eat, Drink, and Be Healthy: The Harvard Medical School Guide to Healthy Eating
Walter C. Willett, M.D., with P.J. Skerrett
(Simon & Schuster, 2005)

This book provides state-of-the-art information about the links between diet and health. An extensive selection of recipes helps readers put the latest nutrition findings into practice.

Eat, Play, and Be Healthy: The Harvard Medical School Guide to Healthy Eating for Kids
W. Allan Walker, M.D., with Courtney Humphries
(McGraw-Hill, 2005)

Written by a world-renowned nutrition expert and Harvard professor of pediatrics, this book shows you how to feed your children to ensure that their young bodies and minds enjoy full and healthy growth at every stage of development.

body mass index (BMI): An estimate of the body’s fat content, calculated from measurements of height and weight.

dietary fiber: The edible, nondigestible component of carbohydrates naturally found in plant food.

dietary reference intakes (DRIs): A comprehensive set of standards for daily intake of essential vitamins and minerals, based on evidence from scores of observational and clinical studies.

essential fats: Beneficial polyunsaturated fats, including both omega-3 and omega-6 fatty acids, that come exclusively from foods and supplements; they are not manufactured by the body.

glycemic index: A measure of how soon and how much a serving of a food causes blood sugar to rise. Foods with a high glycemic index are thought to increase the risk of insulin resistance and other health problems.

high-density lipoproteins (HDLs): Spherical particles that transport cholesterol from body cells to the liver and other sites for elimination; called “good” cholesterol because high levels are associated with a low risk for heart disease.

insulin resistance: An adverse condition in which the body does not respond normally to insulin, the hormone that ferries sugar from the blood into the cells. Insulin resistance can lead to type 2 diabetes and heart disease.

low-density lipoproteins (LDLs): Spherical particles that transport cholesterol in the blood; called “bad” cholesterol because high levels are associated with a high risk for heart disease.

macronutrients: The basic categories of nutrients that humans need for energy and metabolism: fat, carbohydrate, and protein.

micronutrients: The vitamins and minerals that humans need to maintain normal body functions and prevent certain illnesses.

monounsaturated fats: Beneficial fats that contain one double bond between adjacent carbon atoms.

omega-3 fatty acids: Beneficial fats also known as n-3 fatty acids. These are polyunsaturated fats in which the last double bond between carbon atoms is located three carbons from the end of the chain.

omega-6 fatty acids: Beneficial fats also known as n-6 fatty acids. These are polyunsaturated fats in which the last double bond between carbon atoms is located six carbons from the end of the chain.

phytochemicals: Substances made by plants that have biological effects in the human body. Some are phytoestrogens, chemicals that behave like (or sometimes block the action of) the hormone estrogen.

polyunsaturated fats: Beneficial fats that contain two or more double bonds between adjacent carbon atoms.

saturated fats: Unhealthy fats in which all the carbon atoms are bonded to the maximum number of hydrogen atoms so there are no double bonds between the carbons.

trans fatty acids (trans fats): Unhealthy fats that occur naturally in meat but come mainly from processed foods made with hydrogenated oils. Hydrogenated oils are polyunsaturated fats that have been chemically altered to be made more like saturated fats.

triglycerides: Fat that is transported through the bloodstream. High levels increase the risk of heart disease.

Faculty Editor
Teresa Fung, Sc.D., R.D., L.D.N.
Adjunct Associate Professor, Harvard School of Public Health
Associate Professor of Nutrition, Simmons College

Sandra Gordon
Susan Gilbert

Editor, Special Health Reports
Kathleen Cahill Allison

Art Director
Heather Derocher

Production Editors
Mary Kenda Allen
Melissa Rico

Alex Gonzalez
Scott Leighton

Published by Harvard Medical School
Anthony L. Komaroff, M.D., Editor in Chief
Edward Coburn, Publishing Director

In association with Belvoir Media Group, LLC
Robert Englander, Chairman and CEO
Timothy H. Cole, Executive Vice President and Editorial Director

Permissions requests
Natalie Ramm

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Bulk sales
Tonya Phillips

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