PREVENTION OF COLONIC ABERRANT CRYPT FOCI AND MODULATION OF LARGE-BOWEL MICROBIAL ACTIVITY BY DIETARY COFFEE FIBER, INULIN AND PECTIN

The present experiments were aimed at developing novel dietary fibers to aid in reduction of colon cancer risk. We assessed the effects of c offee (non-fiber fraction), coffee fiber (arabino-galactose polymer) a nd inulin (oligo-fructose) in male F344 rats using formation of azoxym ethane (AOM)-induced aberrant crypt foci (ACF) in the colon as the mea sure of preventive efficacy (or lack of such). At 5 weeks of age, grou ps of rats were fed the AIN-76A (control) and experimental diets that contained 1% coffee, 10% coffee fiber, 10% inulin, 10% pectin (positiv e control for fiber) or 200 p.p.m. piroxicam (a known ACF inhibitor). At 7 weeks of age, all animals were s.c injected with AOM (15 mg/kg bo dy wt) once weekly for 2 weeks, All rats were killed 8 weeks after the last AOM injection and ACF were counted. The contents of the cecum we re analyzed for bacterial beta-glucuronidase activity and short-chain fatty acids (SCFAs). Dietary administration of coffee fiber significan tly suppressed AOM-induction of colonic ACF, in terms of total number, as well as crypt multiplicity and number of ACF/cm(2) colon (P < 0.01 -0.001). Inulin diet had no significant effect on total ACF, but had r educed the number of ACF/cm(2) (P < 0.05). Whereas coffee had no effec t on ACF formation, 10% pectin diet and 200 p.p.m. piroxicam significa ntly suppressed colonic ACF (P < 0.001) as had been expected. A signif icant reduction of cecal beta-glucuronidase activity was observed in t he rats fed coffee, coffee fiber and pectin diets. Further, coffee fib er, inulin and pectin increased cecal SCFA levels 3- to 5-fold. These results suggest that coffee fiber can prevent colon cancer risk, Furth er studies are warranted to determine the full potential of this fiber in pre-clinical efficacy studies.