Reducing Riskeat A Healthy Diet - Chapter 3 Reducing Your Cancer Risk: Cancer

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Reducing risk-Eat a healthy diet

About one-third of all cancer deaths are caused by dietary factors. But constantly changing news reports about foods that might cause or prevent cancer make it difficult to choose the best diet. Fear not - there are some clear guidelines, based on solid research, to help guide you toward a prudent diet.

Your parents were right when they told you to eat your vegetables! The ideal diet for cancer prevention includes lots of fruits, vegetables, and whole grains, but not a lot of red meat. Rather than focusing on one or two "buzz-foods" that might protect the body from cancer, follow these food guidelines - and maintain a healthy weight - and you'll have the keys to a cancer prevention diet.

Eat more fruits and vegetables

Eating plenty of fruits and vegetables appears to be vital to good health. These foods not only supply a variety of essential vitamins and minerals, but they also contain substances known as phytochemicals, which protect against cancer. Scientists are now looking at particular foods to determine which substances they contain and why they reduce the risk of cancer.

The American Institute of Cancer Research convened an expert panel in their Second Expert Report issued in 2007 that reviewed hundreds of epidemiological studies on dietary intake of fruits and vegetables. The results provide overwhelming evidence that fruit and vegetable consumption reduces the risk of cancer.

Cooked or raw? Few studies have compared raw and cooked vegetables in terms of the protection they offer. Cooking spinach may confer greater protection than eating it raw simply because the leaves wilt, so you get more cooked spinach per serving.

Eat more bread, beans, and bananas. The second overall recommendation is to eat more of the types of foods that will fill you up, while at the same time providing a variety of vitamins, minerals, protein, complex carbohydrates, and fiber. Such foods include whole grains, found in breads, cereals, pasta, and rice; legumes, such as beans and peas; plantains, such as bananas; and roots and tubers, such as sweet potatoes. Look for foods that have been minimally processed and that contain few refined sugars; such foods are generally the best sources of nutrients and other beneficial substances. For example, whole grain wheat bread is better than white, and bran cereal is better than cereals with frosting or that taste like chocolate.

Some people worry about gaining weight if they eat too many carbohydrates, but if you don't overdo it, you should be fine. A serving of pasta, for instance, is not a plateful - it's ½ cup, cooked. A serving of cereal is ¾ cup dry or ½ cup cooked. The payoff of a diet high in grains and beans is that you will receive a variety of nutrients that help reduce your risk of cancer. Sweet potatoes contain vitamin C and carotenoids, for instance, and beans contain folate.

These foods also provide fiber, long believed by researchers to be a key ingredient in a cancer prevention diet. When it comes to colon cancer, for instance, the theory has been that fiber helps reduce risk by moving waste products through the bowel more quickly, lessening the time that the body is in contact with carcinogens. However, two respected clinical trials published in the New England Journal of Medicine cast doubt on the protective role of fiber. Both studies looked at ways to prevent the recurrence of benign polyps - which, if left untreated, could become cancerous - in people who had already had such polyps removed. One study looked at whether any protection was offered by a low-fat, high-fiber diet; the other at that offered by a high-fiber cereal supplement.

Both studies concluded that dietary fiber on its own was not enough to prevent someone from developing more benign polyps. These studies buttressed the findings of a number of previous trials, which had also questioned the protective role of fiber. But these experiments were narrowly focused, and physicians and nutritionists are not ready to dismiss fiber altogether because it remains part of an overall healthy diet.

Eat less red meat. Diets high in saturated fat (in particular, animal fats) increase the risk for some cancers. In particular, eating red meat increases the risk for colorectal cancer in both men and women. Although many people grew up on a steady diet of red meat, no one needs to have meat on a daily basis. Most Americans consume more protein than they need. Even a wholly vegetarian diet can provide ample protein.

Cook meats safely. The way that meats are cooked is also important. Known or suspected carcinogens are formed when meat or fish is exposed directly to flame or intense heat, as typically happens when food is broiled, roasted, fried, or grilled. High temperatures and flames induce chemical reactions as oil and fat drip down, forming new compounds that splatter back up and stick to the surface of the meat. These compounds include polycyclic aromatic hydrocarbons (PAHs) and heterocyclic amines (HAs), which are known carcinogens in animals and are suspected of being carcinogenic in people. (Derivatives of PAH are also found in tobacco smoke.) Epidemiological studies have reported that people who frequently eat meats cooked at high temperatures may increase their risk for stomach and colorectal cancers.

Fortunately, this particular cancer risk can be controlled and should be kept in perspective. It is important that foods, and especially meats, be cooked thoroughly to kill any bacteria, and for people trying to reduce their risk of heart disease, eating broiled or grilled food is often recommended. In order to reduce your risk for cancer, don't regularly eat meat that has been overcooked or charred. Eating such foods on an occasional basis won't greatly increase your risk for stomach and colorectal cancers. There are other strategies as well. Grill vegetables instead of meat. (Since the vegetables don't drip fat, cooking them doesn't create the compounds discussed above.) Choose lean cuts of meat, or trim off the fat and skin before cooking. Turn the meat often while cooking, and use tongs or a spatula, which does not puncture the meat (allowing more fat to drip down). Choose broiling or grilling, where drippings fall away from the meat and may not splatter up as much, over pan frying - where the meat is in direct contact with both high heat and fat drippings, resulting in the formation of more carcinogens on the meat surface. Or precook meats by boiling, steaming, or microwaving to lessen the amount of time spent grilling.

Limit cured meats. Processed cold cuts (luncheon meat), hams, and hot dogs contain nitrites and nitrates as preservatives. Based on animal studies, researchers have concluded that nitrites in particular may be changed to cancer-causing nitrosamines in the stomach, which presumably could increase the risk of stomach cancer. Foods preserved by salting, pickling, and smoking also contain substances that may increase cancer risk. But thus far the evidence - based variously on studies of animals and people, here and abroad - is contradictory. Some studies report that diets high in cured meats may increase the risk of colorectal cancer, but others disagree. Similarly, although some studies have addressed the effects of such diets on stomach and pancreatic cancers, the evidence is insufficient to reach any firm conclusion.

So what should you do? The strategy best calculated to reduce your risk of cancer would be to eat cured meats only in moderation. It is unlikely that the occasional hot dog or ham sandwich will materially affect your cancer risk.

Keep your weight in check

One of the most important ways to reduce cancer risk is to avoid becoming overweight or, if you already are, to lose those extra pounds and maintain a healthful weight. At the very least, try not to gain any more weight. Obesity causes breast cancer in women who are past menopause, and a number of other cancers, as well as heart disease, diabetes, and other health problems.

Why are so many people overweight? Many experts believe a great deal of it is due to lack of activity. We watch television, work long hours at the computer, take the elevator, and even open the garage door with the push of a button. Many modern-day conveniences rob us of opportunities to burn calories. While the opportunities to exercise are decreased, our food supply is plentiful. Staying at a healthful weight means maintaining a balance between the energy (calories) we take in by eating and the energy we burn up in activity. To lose weight and maintain a healthful weight, regular exercise is vital. If you need help in losing extra weight, start by talking with your physician. You may also be able to find a program in your community that offers group support or other assistance.

Last updated:	May 01, 2008