Diet Focus

One of the most important things you can do to reduce your risk of cancer is also one of the simplest: eat right. If that sounds too easy, rest assured that it is one of the most critical factors in preventing cancer. In fact, medical research tells us that diet and nutrition factors can influence 70 percent of all preventable cancers and 35 percent of cancer deaths in the U.S.

Many dietary factors can affect cancer risk: types of foods, food preparation methods, portion sizes, food variety, and overall caloric balance. Cancer risk can be reduced by an overall dietary pattern that includes a high proportion of plant foods (fruits, vegetables, grains, and beans), limited amounts of meat, dairy, and other high-fat foods, and a balance of caloric intake and physical activity.

So what are you waiting for? Dig into those fruits and vegetables, bring on the onion and garlic, and munch on more grains and nuts. Those are just a few of the foods that contain plant chemicals that have been shown to keep us healthy.

What is Cancer?

There are over 200 known types of cancer. Simply put, all cancers involve the uncontrolled growth of abnormal cells derived from normal tissues, which eventually can cause death by spreading from the site of origin to other sites. Warning signs can include:

• a change in bowel or bladder habits
• a sore that does not heal
• unusual bleeding or drainage
• thickening or lump in the breast or elsewhere
• indigestion or swallowing difficulty
• a change in a wart or mole
• persistent cough or hoarseness

Risk Factors

While your diet can have a major influence on your risk for cancer, it is only one of several lifestyle factors that play a role. Unlike hereditary risks, diet and other lifestyle factors are completely within your power to control. In general, it is suggested that you follow the following guidelines:

1. Nutrition: Eat the right foods, get the right nutrients. Read on to learn more.
2. Smoking: Quit. Period.
3. Sun: Avoid overexposure to dramatically reduce your risk of skin cancer.
4. Exercise: Remember, it is an important part of any healthy lifestyle.

Different cancers have different risk factors. For example, smoking is a risk factor for cancers of the lungs, mouth, throat, larynx, bladder, and several other organs. Unprotected exposure to strong sunlight is a risk factor for skin cancer.

One particular cancer in which diet can really make a difference is colon cancer. It's the second biggest cancer killer in men (after lung) and the third in women. Studies have repeatedly shown that individuals who stick to a diet low in saturated fats and high in fruits, vegetables and grains have significantly lower risk of colon cancer. A major component in reducing the risk of colon cancer is to cut back on the saturated fats in your diet, particularly from red meats.

Prostate cancer is another cancer in which diet appears to play a significant role in prevention. It is the fourth most common cancer. There is a definite link between a high-fat, high protein diet and prostate cancer. Therefore, cutting back on fatty meats--particularly red meats--will reduce a man's risk of developing prostate cancer. (Meat eaters have two and a half times the rate of prostate cancer than do vegetarians.) Also, a recent study of Italian men found that those who had increased their consumption of tomato sauce had a decreased incidence of prostate cancer. Tomato contains the phytochemical lycopene, a substance that researchers believe keep cancer cells from forming or attaching to healthy cells. You should also cut down on fats from milk and milk products, such as whole-milk ice creams and cheeses. And studies on Japanese men (who historically have much lower rates of prostate cancer than American men) suggest there is a food compound called genisten that may also help protect men against prostate cancer. Genisten can be found in soybeans, soy meal and tofu.

What you eat also may have a great influence on whether or not you develop stomach cancer--which has a very low 5-year survival rate of only 16 percent. Stomach cancer is more common in some parts of the world--such as Japan, Korea, parts of Eastern Europe and Latin America--than in the United States. People in these areas eat many foods that are preserved by drying, smoking, salting or pickling. In Japan, which boasts an overall low cancer rate, stomach cancer causes more deaths than all other malignancies combined and is almost six times more common than it is in the United States, presumably because of all the pickled, salted, barbecued and smoked foods that the Japanese eat. Researchers believe that eating foods preserved in these ways may play a role in the development of stomach cancer. Other studies have suggested that fresh foods (particularly fresh fruits and vegetables and properly frozen or refrigerated fresh foods), may actually protect against disease.

Consuming large amounts of alcohol is also a diet risk factor in some cancers, such as liver cancer, esophagus and mouth cancer, and, to a lesser degree, breast cancer.

All cancers caused by cigarette smoking and heavy use of alcohol could be prevented completely. The American Cancer Society (ACS) estimates that in 1999 about 173,000 cancer deaths are expected to be caused by tobacco use. This accounts for about one third of all cancer deaths. An additional 20,000 cancer deaths are related to excessive alcohol use, frequently in combination with tobacco use.

What Nutrients Can Do for You

Nutrients can influence cancer on many levels -- from whether it develops at all, to how it proliferates if it does. Most of what we know about nutrition and cancer is based on the results of a variety of medical research studies.

Fat and Calories
Although the link between fat intake and cancer is weak at best, some studies have shown that animals on low-fat diets have a lower incidence of cancer and a slower pace of tumor growth.

The research seems to support the idea that monounsaturated fat from sources such canola oil and olive oil may decrease the risk of cancer, while polyunsaturated fat from sources such as corn oil or safflower oil can increase the risk.

In animal studies, the effect of reducing total calories by 30 percent decreased the incidence of cancer in half the control subjects. Cutting calories may be one of the simplest ways to reduce the risk of cancer. However, it may not be such a good idea for people who already have it. Tumor growth can rob a patient of much energy, so it is important to have enough calories in the diet to prevent weight loss and wasting.

Fiber
More than 40 studies support the idea that fiber can protect against colorectal cancers. Wheat bran, for example, is a fiber that reduces or dilutes the bile acids that are known to promote cancer in the colon.

On the other hand, corn bran, pectin and agar may increase, rather than inhibit, colon cancer. (Whether a fiber increases or decreases the risk of cancer depends on what bacteria it supports in the colon, and what enzymes these bacteria product that might activate or prevent the initiation of cancer.)

The protective effects of fiber are associated with eating fiber-rich foods and not with taking fiber supplements. To help prevent cancer, get your daily dose of 25-30 grams of fiber from sources like whole-grain foods, fruits and vegetables, and dried beans.

As you increase your intake of fiber, you generally tend to decrease your intake of total fat and calories, perhaps providing an even greater measure of protection against cancer.

The ACS stresses a diet of high fiber foods: at least 6 servings a day. High-fiber foods include whole-wheat breads, macaroni, brown rice, corn, cereals and bran cereals, and air-popped popcorn. Also beans and legumes, such as chick peas, black beans, broad beans, kidney beans, lentils and pinto beans; dried fruits like dates, figs, prunes and raisins; fresh fruits, especially apples, pears, raspberries, blueberries, blackberries and strawberries; and fresh vegetables, particularly squashes, snow peas, uncooked spinach leaves and baked potatoes (with the skins left on).

The key to tolerating high-fiber diets is to first increase your fiber content gradually; otherwise, you may suffer cramps and unpleasant gas. It is also essential to drink at least 8 glasses of liquids per day (water, fruit juices and sodas count, but not tea or coffee because of their diuretic effects.) If you don't, you will likely find yourself constipated, despite the high fiber intake.

Non-nutrient food components
Catechins in teas, sulforaphane in foods like broccoli and cabbage, and amyl sulfides found in garlic and onions all have been identified as providing protection against cancer.

Limonoids in citrus fruits, isoflavones in soy foods, lycopenes in tomato and polyphenols in tea also provide a variety of healthful properties in preventing cancer.

Idoles, monoterpenes and isothiocyanates are potential cancer-fighters; they occur naturally in fruits and vegetables, soy products and teas, particularly green teas.

Protein
Protein does not seem to be a major factor in cancer once normal protein intake and protein quality have been assured. However, there is a consistent and strong relationship between the consumption of protein-rich red meat and the incidence of cancers of the colon and rectum. It is a good idea to limit red meat consumption on a daily basis and to rely instead on other sources of protein (such as chicken and fish). Selenium
Selenium intakes have been found to be low in cases of various cancers, including breast, gastrointestinal and colorectal cancers, as well as lymphomas and leukemia. Higher levels of dietary intake are associated with decreased risk of cancer in general and of lung, colorectal and prostate cancers in particular.

Selenium is found in seafood, meats (especially organ meats), garlic and whole grains. However, since reducing how much meat you eat is also a cancer-fighting strategy, you may want to get your selenium from an alternative source, like grains. The best way to get enough selenium is to eat foods which contain it or to take a multi-vitamin pill which contains it. The recommended daily amount is 55 micrograms for women and 70 micrograms for men.

An important caveat: Selenium is toxic at even low concentrations (as low as 1000 micrograms a day); in toxic amounts it can cause hair loss, gastrointestinal upset, and peripheral nerve damage. To avoid excessive doses, rely on foods and multi-vitamin sources for selenium; never resort to taking selenium supplements.

Vitamins
Low levels of vitamin A may increase the risk of skin cancer.

Vitamins C and E and beta-carotene are anti-oxidants which help prevent cancer by inhibiting the formation and growth of tumors. Fruits and vegetables rich in beta-carotene have also been shown to reduce the risk of cancer in the larynx, esophagus and lungs. For foods rich in beta-carotene, think particularly about dark yellow or orange fruits and vegetables, and green leafy vegetables, such as dried apricots, cantaloupe, carrots, cooked collards, uncooked spinach leaves, fresh parsley, peaches, pumpkin and sweet potatoes.

Vitamin C enhances the immune system and may reduce the cancer-causing potential of pesticides, heavy metals and industrial-use hydrocarbons by helping to detoxify these compounds.

Vitamin D has been found to make cells less resistant to chemotherapy.

A decreased intake of vitamin E is associated with lung, colorectal, stomach and bladder cancers.

Deficiencies in the so-called "lipotropes" -- B12, folic acid, choline, methionine -- may increase susceptibility to chemically induced cancers.

Effects of Other Substances
Copper, manganese and zinc are elements which have the notably beneficial effect of inhibiting tumor growth associated with cancer. They are also needed for anti-oxidant enzymes to do their work.

There may be a link between high iron in the diet, with high transferrin saturation in the blood, and cancers of the lung, colon, bladder and esophagus.

What You Can Do

Improve your odds against cancer -- eat right, exercise, watch your weight and don't smoke -- and you will be 60 percent less likely to get cancer. Remember, one-third of cancer deaths in the United States may be linked to how people eat. Here are some general recommendations you might want to follow:

1. Eat a plant-based diet -- Eat a plant-based diet, rich in a wide variety of fruits, vegetables, legumes and minimally-processed complex carbohydrates. Plant foods are established cancer-protectors because they are loaded with fiber, vitamins, minerals, anti-oxidants and phytochemicals. The less red meat and calories you eat, the better.
2. Avoid gaining weight as you age -- Ten pounds during adulthood is acceptable. The risk for health problems increases for those who gain weight. Endometrial cancer, kidney cancer, and breast cancer risk have been linked to weight gain.
3. Eat fruits and vegetables -- Eat five a day of fruits and vegetables all year. Green leafy vegetables and citrus fruits have compounds that are potent-cancer fighters. All fruits and vegetables play a part in reducing risk of cancers of the lungs, colon, mouth, throat, stomach, breast, pancreas and bladder.

   Vegetables and fruits contain beta-carotene, vitamin C, vitamin E and selenium -- all anti-oxidants that protect cells from damage by free-radicals. These compounds also boost the immune system to fight off infection and cancer.

   The cruciferous family of vegetables-broccoli, cabbage, cauliflower, bok choy, and brussel sprouts, have particular protection against cancer. Tomatoes contain lutein and lycopene, and carrots have carotenoids, which can also help in the fight against cancer.

4. Eat complex carbohydrates -- Eat more than seven servings a day of whole grains, legumes, roots and tubers. Limit foods high in refined sugar. Complex carbohydrate foods offer protection against cancer of the colon, rectum, breast, and pancreas because of their fiber, vitamins, minerals and phytochemicals. Whole grains, brown rice, dried peas and beans, sweet potatoes, beets, turnips, and bananas are particularly powerful. The fiber moves waste through the digestive tract faster, so harmful substances don't have as much contact with your intestinal walls.
5. Limit alcohol -- A moderate amount of alcohol offers protection against heart disease. However, the more alcohol consumed regularly, the higher the incidence of mouth, liver, larynx, and colon cancers. So the higher the intake of alcohol, the grater the risk of cancer. Keep it low: two drinks a day for men, one a day for women.
6. Limit fatty foods -- Especially those of animal origin. Use more monounsaturated fats as part of your total fat intake. Diets high in fat, particularly saturated fat, promote breast, colon, endometrial, lung, prostate and rectal cancers. Fat intake should fall below 30 percent of total calories, and canola or olive oils should replace lard, butter and margarine in the diet.
7. Limit salty foods and use of salt -- The rate of stomach cancer is higher in populations who eat a high-salt diet. Try to limit processed foods and the use of the salt shaker.
8. Only eat foods that are stored properly -- Foods that are stored in warm damp conditions can develop molds, and mycotoxins that may promote liver cancer. Peanuts and grains can develop mycotoxins in commercial storage.
9. Refrigerate perishable foods -- Refrigerated food needs less salt for preservation, thus reducing the risk of stomach cancer.
10. Do not eat charred foods -- Don't eat overly crisp grilled meats and fish. Very high heat on protein foods can produce cancer causing heterocyclic aromatic amines. These compounds have been linked to colon and rectal cancers.
11. Drink tea -- Green and black tea have polyphenols, specifically catechins, which prevent cancerous cells from growing and may even destroy them.
12. Give soy a try -- Americans do not use soy foods as a staple, but populations who do have less cancer of the breast, prostate, and lung. The substance in soy, genistein, is an isoflavone that appears to protect against cancer. You can increase your isoflavone intake with soy milk, tofu, and the textured soy protein used in veggie burgers.
13. Pile on the onions and garlic -- The pungent flavor from these vegetables come from chemicals called organosulfurs, which detoxify potential carcinogens. Garlic extract has slowed the growth of breast, skin and colon cancers in mice. It seems the raw version of onions and garlic is most useful in cancer protection. More research is needed to determine if supplements are as effective as the food source.
14. Try a little hot spice -- Chile peppers that set your tongue on fire also burn out carcinogens. They contain a potent anti-oxidant, capsaicin, which interferes with the union of nitrites and amines. These nitrosamines are linked to stomach cancer. Also, capsaicin may keep the carcinogens in cigarette smoke from causing the genetic damage that can lead to lung cancer.
15. Finally, do not smoke or chew tobacco -- Though not a diet recommendation, it can't go unsaid that tobacco is the chief cause of lung cancer. A great diet can be protective, but is no insurance policy if you smoke

    The use of alcohol, even in moderate amounts, is associated with increased risk for cancers of the mouth, larynx, pharynx, esophagus, liver, colon, rectum and breast. Women at high risk for breast cancer might consider abstaining from it altogether. There are no known protective effects of alcohol against cancer to counterbalance the known cancer risks of moderate to heavy use.

Putting It All To Work

Changing your diet to help protect against cancer is really as simple as adopting a diet for a healthy lifestyle. It's the kind of diet that you should embrace for more reasons than just one. Avoiding cancer is an admirable goal, but so is lower your cholesterol and blood pressure, maintaining a healthy weight, and having a healthy heart. All of these goals can also be met by following the recommendations outlined in this article. Now, to help you on your way, here are some great recipes that are great for you too!

More Resources

For more information about cancer and what you can do to help reduce your risks of getting it, consult your physician and visit any of the following web sites:

• American Cancer Society
• CancerNet
• National Cancer Institute
• Cancer Information and Support International