PHYSIOLOGICAL-EFFECTS OF RESISTANT STARCHES ON FECAL BULK, SHORT-CHAIN FATTY-ACIDS, BLOOD-LIPIDS AND GLYCEMIC INDEX

Objective: To assess the effects on fecal bulking, fecal short chain f atty acid (SCFA) production, blood lipids and glycemic indices of two different forms of resistant starch (RS2 and RS2) from a high-amylose cornstarch. Methods: Twenty-four healthy subjects (12 men; 12 women) c onsumed four supplements taken for 2 weeks in random order separated b y 2-week washout periods. The supplements were a low-fiber (control) a nd supplements providing an additional 30 g dietary fiber as wheat bra n (high-fiber control) or the equivalent amount of resistant starch an alyzed gravimetrically as dietary fiber from RS, or RS,. Four-day feca l collections and 12-hour breath gas collections were obtained at the end of each period. Fasting blood was taken at the beginning and end o f each period. Glycemic indices of supplements were also assessed. Res ults: The wheat bran supplement increased fecal bulk 96+/-14 g/day com pared with the low-fiber control (p<0.001) with the mean for both resi stant starches also being greater (22+/-8 g/day) than the low-fiber co ntrol (p=0.013). On the resistant starch phases, the mean fecal butyra te:SCFA ratio, which has been suggested to have positive implications for colonic health, was significantly above the low-fiber control by 3 1+/-14% (p=0.035). Resistant starches did not alter serum lipids, urea or breath H-2 or CH4. No significant differences in glycemic index we re seen between the RS and control supplements. Conclusion: The potent ial physiological benefits of the resistant starches studied appear to relate to colonic health in terms of effects on fecal bulk and SCFA m etabolism.