Abstract: Objective To study the effects of resistant starch(RS) on intestinal fermentation in diet-induced obese (DIO) rats，and to clarify the possible mechanism of RS to improve intestinal function.Methods  60 SD rats were divided  randomly into 2 groups.One of the groups was selected as control group,and the rats were fed with normal foods.The rats in the other  group were fed with high-fat foods for 7 weeks.The DIO rats were divided into five groups,and were fed,for 5 weeks,respectively with high-fat foods,hight-fat foods containing 5% RS,10% RS,15% RS,and 10% RS plus dextran sulfate(DS) as inhibitor to butyric acid.Then,small intestinal and cecal tissue and cecal contents were collected,and body weight gain,the ratio of fat to body,cecal area and weight,amount of short chain fatty acids（SCFA）and pH in cecal contents were determined.Results Compared with control group,the body weights,ratio  of fat to body and pH of cecal contents of the rats in 10%RS group and 15%RS group were decreased(P<0.05 )；the cecal area  in 15%RS group was increased(P<0.05).The acetic acid,propionic acid and butyric acid levels in faeces in 5%,10% and 15%RS groups were increased(P<0.01).The weights of cecal contents in 10%RS group and 10%RS+DS groupwere decreased （P<0.05）.The acetic acid and propionic acid levels in faeces in 10%RS+DS group were increased （P<0.01）.The dose of RS was negatively related to the rat body weight (r=－0.862，P<0.01) and was positively related to the levels of acetic acid,propionic acid and butyric acid in cecal contents of rats(r₁=0.945，r₂=0.943，r₃=0.949，all P<0.01).Conclusion RS may significantly increase the cecal area，reduce the pH of cecal contents and increase short chain fatty acid levels in faeces.It is certified that RS can improve intestinal fermentation function of DIO rats.

Key words: resistant starch, diet-induced ob
ese rats, intestinal fermentation, short chain fatty acid