K. Tebib et Jm. Rouanet, EFFECTS OF DIETARY GRAPE SEED TANNINS ON RAT CECAL FERMENTATION AND COLONIC BACTERIAL ENZYMES, Nutrition research, 16(1), 1996, pp. 105-110
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.