Feeding the Fight Against Cancer

Cancer etiology is a mixed bag of genetics and environment. While people cannot change their genetic make-up, they can control aspects of their life that foster cancer development. The American Institute for Cancer Research (AICR), Washington, D.C., relates 30% to 40% of cancers to diet, weight and lack of physical activity. The World Health Organization, Geneva, confirmed this in its report, “Diet, Nutrition and the Prevention of Chronic Diseases” (April 2003). Both organizations recommend a diet high in fruits and vegetables and moderate in meat and alcohol consumption, as well as daily physical activity and maintaining a healthy weight.

Most research on the link between diet and cancer comes from large population studies evaluating the effect of eating patterns on the incidence of specific cancers. The biological mechanisms responsible for protection or damage remain unclear. Frequently, clinical trials testing the proposed active component in a food yield inconclusive or contradictory results. Nonetheless, meta-analysis of data from thousands of studies provides strong evidence that diet and physical activity are key in preventing many common cancers, while obesity poses a risk for developing cancer.

The AICR emphasizes plant-based diets, which include whole grains, legumes, fruits and vegetables, and it’s no wonder. Fruits, vegetables and whole grains are high in fiber, antioxidants and other phytochemicals associated with decreased cancer risk. The bulk of research examining the link between fiber and colorectal cancer shows that people who consume a diet high in fiber-containing foods have less risk for the disease. Other studies indicate that diets high in fruits and/or vegetables protect against cancers of the oral cavity, larynx, esophagus, pancreas, lung, stomach, bladder, breast, colon and rectum.

Broccoli, tomatoes and garlic are just some examples of vegetables linked to protection against cancer. Broccoli and other cruciferous vegetables contain sulforaphene, an antioxidant associated with anticancer activity. These vegetables also contain other compounds with the potential to thwart prostate cancer and detoxify bacteria associated with gastric cancer. Tomatoes and other red vegetables and fruits contain lycopene, which exhibits strong antioxidant activity and is associated with protection against prostate cancer. And garlic consumption is associated with a lower risk for prostate and other cancers. In general, members of the garlic/onion family contain various substances that may help fight cancer.

Soy contains many components that may contribute to cancer prevention. Asians, who typically consume soy products, have a lower incidence of breast and prostate cancer.

There are two opposing views about soy and breast cancer. One claims that soy exerts anti-estrogenic effects that can help prevent breast cancer. The other claims that soy acts as a weak estrogen and poses a concern for women with estrogen-receptor-positive breast cancer. To date, animal and human studies are inconclusive on the role soy plays in breast-cancer risk in women, but there is evidence that eating soy during adolescence may protect against breast cancer as an adult.

Additional research on soy protein and isoflavones indicates soy may help prevent prostate and colon cancer. Recent preliminary data from research conducted at the University of California- Davis and presented in April 2003 at the annual meeting of the Baltimore, MD-based American Urological Association indicates that genistein supplements may help inhibit prostate-cancer growth in men not treated by surgery, radiation or hormone therapy.

Dairy foods present a muddled picture when it comes to cancer. Some research associates milk consumption with an increased risk of prostate cancer, while some does not. One study, “Dietary Correlates of Plasma Insulin-like Growth Factor 1 and Insulin-like Growth Factor Binding Protein 2 Concentrations” (Cancer Epidemiology Biomarkers & Prevention, September 2002), linked high milk consumption with high levels of insulin-like growth factor 1, which is associated with increased risk of prostate, colon, lung and breast cancer. However, another study, “Association of Dairy Products, Lactose and Calcium with the Risk of Ovarian Cancer” (American Journal of Epidemiology, July 2002), indicated that a high intake of skim milk and low-fat milk reduced the risk of ovarian cancer.

Emerging evidence supports a role for dairy as protective against colorectal, breast and other cancers. Calcium, conjugated linoleic acid, vitamin D, sphinomyelin, butyric acid, ether lipids, protein and lactic-acid bacteria are the leading candidates as dairy components with anticancer activity. Lactose, protein and vitamin A may also contribute protection. Current knowledge indicates that consumption of dairy foods in quantities sufficient to provide the recommended daily intake for calcium and vitamin D may provide modest reduction of cancer risk.

There is evidence that diets high in fat and red meat may increase the risk of cancer. New research linking nutrients or foods to cancer appears almost daily. Antioxidants in bread crust, selenium, folic acid, DHA and omega-3 fatty acids recently were highlighted for potential anticancer activity. Ongoing research focuses on individual foods and/or components as scientists study the mechanisms responsible for cancer prevention and define the mix of foods that offers maximum benefits.

To help the average consumer translate current science into action, the AICR advocates the adoption of the “New American Plate,” which aims for meals composed of 2/3 (or more) plant-based foods, such as vegetables, whole grains, fruits and beans; and 1/3 (or less) animal protein, such as fish, meat and low-fat dairy, in sensible portions. Strategic support from food companies and restaurants can help consumers transition to healthier eating through tasty, convenient meals and side dishes that include whole grains, vegetables and fruits in appropriate serving sizes.

Angela M. Miraglio ([email protected]) is a registered dietitian and Fellow of the American Dietetic Association from Des Plaines, IL. Her firm, AMM Food & Nutrition Consulting, provides communications and technical support to food and beverage companies and associations.

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