Effect of dietary wheat bran and dehydrated citrus fiber on 3,2'-dimethyl-4-aminobiphenyl-induced intestinal carcinogenesis in F344 rats.

The effect of dietary wheat bran and dehydrated citrus fiber on 3,2'-dimethyl-4-aminobiphenyl (DMAB)-induced colon and small intestinal carcinogenesis was studied in male F344 rats. Weanling rats were fed semipurified diets containing 5% alphacel, 5% alphacel + 15% wheat bran or 5% alphacel + 15% citrus fiber. At 7 weeks of age, all animals, except vehicle-treated controls, received weekly s.c. injections of 50 mg DMAB/kg body weight for 20 weeks. The DMAB- or vehicle-treated groups were autopsied 20 weeks after the last injection of DMAB. The animals fed the wheat bran diet and treated with DMAB had a lower incidence (number of animals with tumors) and multiplicity (number of tumors/tumor-bearing animal) of colon and small intestinal tumors than did those fed the control diet and treated with DMAB. Animals fed the diet containing citrus fiber developed fewer small intestinal tumors (incidence and multiplicity) than did the rats fed the control diet; the number of adenocarcinomas was reduced in rats fed the citrus fiber diet. This study thus indicates that diets containing wheat bran and citrus fiber reduce the risk for DMAB-induced intestinal cancer and that the protection against colon cancer depends on the type of fiber.