Colonic-rectal cancer: fiber and other dietary factors.

The prevalence of colonic-rectal cancer is generally directly related to the fat content and inversely related to the fiber content of diet. In the few exceptions to this generalization, tumor prevalence is more closely related to fiber than to fat. Hypotheses have been postulated to explain the possible ways in which dietary fiber may protect against colonic-rectal cancer and to account for the close relationships between the geographical distribution of these tumors and that of certain other diseases.