Dietary fiber and cancer prevention

A large body of literature suggests that eating a variety of foods containing high fiber has a protective effect against colon cancer. Evidence also indicates that a high fiber-containing diet may be protective against breast, ovary, endometrial, and gastrointestinal cancer. The focus of this review is the epidemiologic data for an inverse association between a high-fiber diet and risk for the previously mentioned cancers. Epidemiologic studies are categorized as international, within country, metabolic, time trend, case control, and cohort. Since 1980, 32 studies have assessed the role of fiber-containing foods in relation to colon cancer. Among these studies, 25 showed an inverse association. Of the seven case-control studies, which evaluated the relationship between the fiber-rich diet and breast cancer, six demonstrated an inverse association. For cancers of the esophagus, mouth, pharynx, stomach, rectum, endometrium, and ovary, there are only a limited number of studies, most showing a protective effect from eating a diet high in fiber-containing foods. The epidemiologic studies reviewed previously focus on dietary patterns in which fiber-rich foods usually occur as a complex mixture with other foods and food components, thus making it difficult to assess at this time if the protection is clearly from fiber per se or some other dietary component, such as low fat. For cancer prevention, the emphasis for dietary recommendation should be on a dietary pattern rather than on an isolated dietary fiber supplement.