Effects of selenium on colonic fermentation in the rat

Studies were conducted to determine the effects of dietary selenium (Se) on the hindgut microbial activity in rats. Selenium was fed as L-selenomethionine (SeMet) at either 0 or 2 ppm Se in the presence or absence of wheat bran (WB, 10%), a known substrate for the enteric microflora. Wheat bran feeding caused the greatest fermentation, measured by the production of short-chain fatty acids (SCFAs) along the entire intestinal tract and feces; however, its effects were suppressed by SeMet in the proximal large bowel, cecum, and colon. Selenium significantly enhanced fermentation in the colon and rectum, but not in the cecum or feces. Selenium was found in association with the bacterial cell fractions of gut contents and feces: 40-46% of the total Se was associated with colonic microbes and 58% in fecal microbes. Increased acetate and reduced butyrate production were driven by the addition of Se regardless of whether WB was fed.