Effect of rice bran on intraintestinal fermentation and cholesterol metabolism in cecectomized rats

Abstract

The effects of rice bran on intraintestinal fermentation and cholesterol metabolism in cecectomized rats were investigated. Male F344 rats, allocated into three groups: cecectomized rats fed rice bran containing 76.3 g water-soluble fiber/kg and 183 g oil/kg (CERB), sham-operated rats fed rice bran (SHRB) and standard rats fed cellulose with 0.5% cholesterol and 0.125% sodium cholate for 1 week. The body weight in the SHRB group was significantly higher than that in the CERB group and the food intake in the SHRB group was significantly lower than in the cellulose group for 1 week. There were no significant differences in the liver weight among groups. The fecal excretion in the CERB group was significantly higher than that in the cellulose group. The fecal pH in the SHRB group was the lowest among the groups. The serum total cholesterol, very low density lipoprotein + intermediate density lipoprotein + low density lipoprotein-cholesterol, high density lipoprotein (HDL)-cholesterol, triacylglycerol concentrations, and the liver cholesterol concentrations in the CERB and SHRB groups were significantly lower than that in the cellulose group, and the total cholesterol, HDL-cholesterol and liver cholesterol concentrations in the SHRB group were the lowest among the groups. There were no significant differences in the fecal neutral sterol and total bile acid extraction among the groups. The fecal propionic acid, butyric acid and total short-chain fatty acid concentrations in the SHRB group were significantly higher than those in the other groups. Escherichia coli ( E. coli) in the fecal microflora was the main bacterium in the CERB and cellulose groups. On the other hand, Lactobacillus in the fecal microflora was the main bacterium in the SHRB group. The results of this study demonstrate that the rice bran was fermented in the cecum and that the metabolites such as propionic acid and butyric acid, and rice bran oil may be effective in lowering cholesterol levels in the presence of excess cholesterol in the diet.