Dietary resistant starch and acarbose reduce body weight gain in rodents

Abstract

Resistant starch (RS) resists digestion in the small intestine thus increasing the amount of starch available for microbial fermentation producing short chain fatty acids in the colon. Additionally, RS has been shown to reduce body fat in rodent models through mechanisms possibly related to colonic fermentation pathways. Acarbose, an α‐glucosidase inhibitor used to treat Type 2 diabetes, inhibits starch digestion in the small intestines, thus undigested starch reaches the colon mimicking the effects of RS. In this study, we compared changes in fermentation and body fat in rats fed diets with RS or acarbose (AC). Thirty female retired breeder rats were placed in 3 treatment groups (control, 30% RS, 0.4% AC) and fed energy balanced diets (20% fat, 3.7kcal/g) for 12 weeks. Dietary RS and AC reduced body weight and body fat gain. The control group gained 20g, compared to no gain for AC and a 20g loss for RS. Both RS and AC had larger full GI tracts, indicating reduced starch digestion; however, only RS had lower pH of cecal contents indicating only RS increased colonic fermentation. Acarbose seems to prevent starch digestion in the small intestine and starch fermentation in the large intestine. At the doses used, both RS and AC were effective in preventing weight gain, but the greater effect of weight loss with RS may be due to fermentation. Funding by LSU AgCenter.