Cancer and Your Diet

Diet is just one factor in assessing your risk for cancer. That's because there are more than 100 types of cancer, with many different causes. And the average American diet has many components -- some of which may lower the risk for cancer, while others may raise it.

Health experts agree there is one general approach that may help reduce your risk for developing cancer: Adopt a healthy lifestyle that includes getting regular exercise, eating a balanced diet, limiting alcohol, controlling weight and not smoking. A lack of exercise, for instance, is associated with increased risk for colon and breast cancer. Excessive alcohol consumption has been linked to an increased risk for oral, esophageal, breast and other cancers. Obesity is associated with an increased risk for colon, breast, endometrial and possibly other cancers.

The National Cancer Institute says more research is needed to determine whether diet, alcohol and obesity are causes and whether avoiding these behaviors would actually reduce cancer. The exception is tobacco use. The American Cancer Society (ACS) says cigarettes, cigars, pipes and smokeless tobacco cause cancer and should not be used.

How does diet affect cancer risk?

Several dietary factors may affect cancer risk. Type of food is one factor. Diets that include plenty of plant foods such as whole grains, vegetables, fruits and beans, which are rich in antioxidant vitamins and minerals and other phytochemicals, may reduce risk for some types of cancer. In addition, some studies have linked a diet high in animal products such as red meat with an increase in cancer of the colon and prostate.

Obesity is another risk factor for cancer that is affected by diet. Consuming more calories than you need can lead to obesity. Physical activity has a doubled impact here -- it not only helps reduce the risk for obesity, it also independently helps reduce the risk for developing certain cancers.

Cooking certain meats at high temperatures creates chemicals such as heterocyclic amines (HCAs) that are not present in uncooked meats. These chemicals may increase the risk for cancer. Researchers have identified 17 different HCAs that form when amino acids, the building blocks of proteins, and creatine, a chemical found in muscles, react at high cooking temperatures.

Drinking water with a concentration of 0.05mg/L or more of arsenic for many years may increase the risk for lung, skin and bladder cancer, according to the World Health Organization.

Role of dietary fat in cancer

The role of dietary fat in the development of cancer, if any, is still unclear. Research suggests that high-fat diets may increase risk for some cancers in some people. But other influences, such as that people who eat high-fat diets tend to be heavier and eat more calories and fewer fruits and vegetables, may play a greater role in the development of cancer.

According to the ACS, high-fat diets may be associated with an increased risk for cancers of the colon and prostate, but not of the breast. It might be the type of fat in the diet, rather than the total amount of fat, that is most important.

How types of fats affect cancer risk

It's not yet clear how saturated, monounsaturated or polyunsaturated fatty acids may affect cancer risk. Although several animal studies suggest polyunsaturated fats may increase tumor growth, no relationship has been found between polyunsaturated fats and cancer in humans. Likewise, studies in animals have found that omega-3 fatty acids suppress cancer formation, but there is no direct evidence that this occurs in people. There is no evidence that the intake of trans fats affects the risk for cancer.

Cancer prevention tips

• Eat a variety of foods. To make sure you get all of the nutrients and other substances needed for health, choose the recommended number of daily servings listed in the U.S. Department of Agriculture's Dietary Guidelines for Americans.

• Balance the food you eat with physical activity to maintain or improve your weight. If you are sedentary, try to become more active. If you are already very active, try to continue the same level of activity as you age. If your weight is above the healthy range, try to reduce health risks through better eating, slow weight loss and improved exercise habits.

• Choose a diet with plenty of grain products, vegetables and fruits. Eat more whole-grain products (breads, cereals, pasta, rice), vegetables, fruits, beans, lentils and peas.

• Choose a diet low in fat, saturated fat and cholesterol. Some dietary fat is needed for good health. To keep fat intake in a healthy range, use fats and oils in moderation, and frequently choose lean and lower-fat foods. The Nutrition Facts label helps you choose foods lower in fat, saturated fat and cholesterol.

• Choose a diet moderate in sugars. Use sugars in moderation, or sparingly if your calorie needs are low. Read the Nutrition Facts label on foods you buy. Remember that there are now multiple artificial sweeteners to choose from; you should be able to find one that fits your palate.   

• Choose a diet moderate in salt and sodium. Read the Nutrition Facts label to compare and help identify foods lower in sodium within each group. Use herbs and spices to flavor food. Try to choose forms of foods that are lower in sodium. The USDA guidelines recommend no more than 2,300 mg of sodium per day.

• If you drink alcoholic beverages, do so in moderation, with meals and when consumption does not put you or others at risk.