DIETARY GRAPE SEED TANNINS - EFFECTS ON NUTRITIONAL BALANCE AND ON SOME ENZYMATIC-ACTIVITIES ALONG THE CRYPT-VILLUS AXIS OF RAT SMALL-INTESTINE

The aim of the study was to determine the nutritional and intestinal e ffects of grape seed tannins. For this purpose, tannins were incorpora ted in diets of rats at levels of 0.2 or 2.0% for 31 days in compariso n to a control diet. The animals were pair-fed. Nutritional balances w ere not affected by feeding 0.2% tannins. At the highest dose (2%) gra pe seed tannins reduced growth as well as dry matter (DM) and nitrogen (N) digestibility. In rats fed protein-free diets, 2% tannins signifi cantly increased endogenous fecal N. Starch and fat were well digested in all groups of rats. No changes in organ weights were observed. Duo denal alkaline phosphatase activity (AP) was never affected by tannins . On the other hand, in the jejunum, along the villus-crypt unit, a re duction of AP and sucrase appeared at the tip villus which was balance d by an enhancement of H-3-thymidine incorporation in the middle of th e crypt zone, giving evidence of endogenous N loss. This study did not reveal a major toxic effect of tannins except a reduced DM and N dige stibility; nevertheless tannins directly interfere with mucosal protei ns, thereby stimulating the cell renewal.