Tempe consumption modulates fecal secondary bile acids, mucins, immunoglobulin A, enzyme activities, and cecal microflora and organic acids in rats.

The present study investigated the effect of dietary tempe, a fermented soy product, on the colonic environment of rats fed high-fat (HF, 30 % fat; experiment 1) or low-fat (LF, 6 % fat; experiment 2) diets. Growing male rats were fed the experimental diets with or without 25 % tempe for 21 days. Tempe consumption slightly but significantly increased the growth of rats fed both the HF and LF diets (P < 0.05). With both the HF and LF diets, dietary tempe markedly reduced a harmful fecal secondary bile acid, lithocholic acid (a risk factor of colon cancer) (P < 0.05), and markedly elevated fecal mucins (indices of intestinal barrier function) and immunoglobulin A (IgA, an index of intestinal immune function) (P < 0.05). With the HF diet, dietary tempe increased cecal acetate, butyrate, propionate, and succinate concentrations (P < 0.05). Analysis of the profile of cecal microflora revealed lower Bacteroides and higher Clostridium cluster XIVa levels in the tempe group of rats fed the HF diet (P < 0.05). Compared with the control group, the fecal activity of β-glucosidase was markedly higher in the tempe group (P < 0.05), while that of urease was lower (P < 0.05) with both the HF and LF diets. The present results suggest that tempe consumption modulates the colonic environment in rats.