Nutritional strategies in the prevention of colorectal cancer.

A variety of dietary factors have been implicated as agents that can modulate the development of malignancies of the gastrointestinal tract, particularly colorectal cancer. The effects of fat, red meat, fruits, vegetables, and alcohol on colorectal carcinogenesis have been examined extensively and appear to play substantial roles. Although fiber may play a protective role, recent studies raise the question of whether the protection is conveyed by other components in fiber-laden foods. Folate, selenium, calcium, and omega-3 fatty acids have emerged as factors more recently but may be equally important agents in nutritional chemoprevention, whereas the role of antioxidant vitamins is less certain. Until more firm data are available, the dietary recommendations provided by the American Cancer Society and the National Cancer Institute are appropriate for use in counseling patients on this issue.