EFFECTS OF DIETARY GRAPE SEED TANNINS ON RAT CECAL FERMENTATION AND COLONIC BACTERIAL ENZYMES

In rats, the effects of a 12-wk supplementation of a purified diet wit h 71 mg/kg monomeric or polymeric grape seed tannins were explored on cecal fermentation and colonic bacterial enzymes. Weight gain was affe cted by addition of polymers to the diet. There was a significant incr ement of volatile fatty acids (VFA) pool and a pH decrease in the ceca l contents of rats fed polymeric tannins, compared to controls. When e xpressed per gram of nitrogen content, the concentrations of all colon ic fecal bacterial enzyme activities tested (beta-glucosidase, beta-gl ucuronidase, mucinase and nitroreductase) were decreased, due to a dil ution effect. In these experimental conditions, monomeric tannins exhi bited neither beneficial nor detrimental effect. On the other hand, th ese results show that although at a low dietary level equivalent of a daily amount of 0.5 L red wine, polymeric grape seed tannins exert a b eneficial cecal metabolic and colonic protective effect.