COMPARISON OF RESISTANT STARCH WITH CELLULOSE DIET ON 1,2-DIMETHYLHYDRAZINE-INDUCED COLONIC CARCINOGENESIS IN RATS

Background & Aims: Epidemiological and experimental studies have shown that dietary fiber may prevent colon cancer. Resistant starch, like d ietary fiber, is not subject to digestion in the small intestine. Howe ver, it is unknown whether resistant starch inhibits colonic carcinoge nesis. In vitro studies have shown that butyrate slows the growth of c ultured colon cancer cells. The effect of resistant starch diet on 1,2 -dimethylhydrazine-induced colonic carcinogenesis in rats was evaluate d, and the colonic butyrate concentration was measured. Methods: Sprag ue-Dawley rats were randomly divided into five groups that were fed di ets containing no fiber, 3% cellulose, 10% cellulose, 3% resistant sta rch, or 10% resistant starch, Colonic carcinogenesis and butyrate conc entration of colonic contents and feces in each diet group were compar ed, Results: Total cancer volume per rat in the 10% cellulose group wa s significantly lower than that in the basal group (109 +/- 54 mm(3) a nd 247 +/- 83 mm(3); P < 0.05), but the other groups showed no signifi cant differences. The butyrate concentration in colonic content and in feces were higher in the resistant starch groups than in the cellulos e groups. Conclusions: The resistant starch diet increased butyrate co ncentration but did not inhibit colonic carcinogenesis, It remains dou btful whether butyrate inhibits the proliferation of colon cancer cell s.