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The public has been bombarded with messages urging everyone to make substantial dietary changes to reduce their risk of cancer. Americans have been led to believe that the link between specific dietary factors and cancer is solid and convincing, and that dietary modification should be top priority in cancer prevention. In actuality:
- Smoking cessation not diet is the single most important factor in cancer prevention. There is no dietary change which will counteract the harmful effects of cigarette smoking. People who believe that they can safely continue to smoke as long as they eat healthful diets are dangerously misinformed.
- A substantial body of epidemiologic evidence associates low intakes of fruits and vegetables with increased risks of cancer. It would be wise for all Americans to make an effort to include fruits and vegetables in their daily diets. Current recommendations call for a minimum of five daily servings of fruits and vegetables; this is a reasonable goal.
- The current scientific evidence does not warrant recommendations for widespread supplementation with antioxidant nutrients (vitamin C, vitamin E and/or beta-carotene). Clinical trials due to be completed within the next decade should provide definitive evidence on whether or not antioxidant supplementation is beneficial. The one major clinical trial that has already been completed is of little relevance to Americans because it was conducted in a population that has dietary habits and disease patterns dramatically different from those in the U.S.
- Reducing dietary fat intake may reduce the risk of colon cancer but not breast cancer. Evidence for other cancer sites is inconsistent. It is possible that effects attributed to dietary fat may actually be due to related factors such as total caloric intake.
- Dietary fiber has not been convincingly linked with reduced risks of cancer. However, fiber does have other health benefits.
- Reaching and maintaining a desirable body weight is an important health priority. Obesity increases the risk of hypertension, diabetes and coronary heart disease. It may also increase the risk of some types of cancer, especially in women.
- Previous recommendations that Americans should minimize consumption of cured, smoked or pickled foods do not have a sound scientific basis.
- "Chemicals" in food including naturally occurring substances, intentional additives and contaminants do not have a significant impact on cancer risk in the United States.
- People who drink alcoholic beverages should do so in moderation. Excess alcohol intake is linked with many health problems, including increased risks of some types of cancer. The current evidence does not warrant a recommendation for abstinence from alcohol for the purpose of preventing breast cancer.