Colon and Rectal Cancers - Dietary Factors

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Dairy Products and Calcium

Milk, Lactose, and Probiotics. In a 2001 study, adults who drank the most milk had the lowest risk for colon cancer. A 2004 study published in the Journal of the National Cancer Institute supports this conclusion. In this review of 10 epidemiologic studies that included more than 500,000 people, those who consumed more milk and calcium had a lower risk of developing colorectal cancer. Milk contains not only calcium but also other compounds, such as lactose, that may help protect against colon cancer.

Yogurt specifically has been associated with a lower risk for colon cancer if it contains live active bacterial cultures, such as Lactobacillus acidophilus, that are called probiotics. These "friendly bacteria" appear to protect the colon from cancerous changes. (Acidophilus and other probiotic capsules are also available in health food stores.)

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Calcium. Calcium, which is found in dairy products, is associated with colon cancer protection. Many studies have shown a possible protective effect from either high-calcium diets or calcium supplements. However, a 2006 study from the Women’s Health Initiative found that calcium and vitamin D supplements do not reduce women’s colorectal cancer risk. Experts still recommend that postmenopausal women take these supplements for bone health.

Total Calories and Sugar

Obesity has been associated with colon cancer. In some studies of people under 67 years old, the amounts of fat and protein were less important than the total number of calories consumed: the higher the energy intake, the greater the risk for developing colon cancer. In older adults, high calorie intake did not make any significant difference. Other studies have indicated that excessive sugar-intake may increase the risk for colon cancer.

Coffee and Tea

Studies conducted in several countries have found that drinking four or more cups of coffee a day is associated with a lower risk for colorectal cancer. Green tea may have beneficial properties, but more research is needed in both of these areas.

Vitamin and Mineral Supplements

Folate and B Vitamins. There is evidence that the B vitamin folate (called folic acid) is protective. Both folate and vitamin B12 convert the amino acid homocysteine to methionine, a chemical that protects certain genes that help prevent cells from becoming cancerous. Folate is found in beans, citrus fruits, and green vegetables, but benefits seem higher when taking supplements. The protective effect appears to be greatest for people who are genetically predisposed to colorectal cancer.

Antioxidant Supplements. Antioxidants are chemicals that help eliminate harmful particles called oxygen-free radicals that have been associated with cancerous changes. Some studies have associated supplements of the antioxidants selenium and vitamins A, C, D, and E with lower colon cancer risk, but most studies have found no protective effect.

Review Date: 03/06/2007
Reviewed By: A.D.A.M. Editorial Team: Greg Juhn, M.T.P.W., David R. Eltz, Kelli A. Stacy. Previously reviewed by Harvey Simon, M.D., Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital (9/1/2006).