Cellulose Dietary Bulk and Azoxymethane-Induced Intestinal Cancer

Summary

A model experiment explored the significance of bulk in colon cancer production. Male Fischer strain rats were fed either a low-residue semisynthetic diet or the same diet containing 20% and 40% of its bulk as cellulose. All animals were given injections of 14.8 mg azoxymethane/kg body weight once a week for 10 weeks and held an additional 16 weeks. The food intake and weight of feces per day were proportional to the inert cellulose content of the diet. Most animals inoculated with the colon carcinogen had tumors in the intestinal tract. However, tumors in the small intestine were fewer than the average number of all intestinal tumors per rat, with the highest number on the semisynthetic diet and progressively lower numbers as the bulk of the diet increased. In the colon there were slightly more tumors per rat when the diet contained 20% cellulose. Thus azoxymethane-induced tumors in the small intestine were more sensitive to bulk and fiber content of the diet than were tumors in the colon.