Large bowel cancer is common in the Western countries and is relatively rare in the developing countries. 2. It is related to diet, probably to dietary meat or fat. 3. It has been postulated that the Western diet results in a high concentration in the large bowel of bile acids and that these are metabolized by the gut bacteria to carcinogens or cocarcinogens. 4. There is evidence in support of this postulate from studies of populations in various parts of the world and from a retrospective case-control study. 5. A role for dietary fiber has also been suggested, but there is little evidence in favor of this.
