Abstract
We have previously reported that the fermentation of dietary beet fiber (BF) in the cecum of male Sprague-Dawley rats plays an essential part in the hypocholesterolemic effect of BF. We have now studied the effect of antibiotics on the BF-mediated hypocholesterolemia. Rats were fed a cholesterol-free diet with or without (fiber-free, FF) BF, together with one of the following antibiotics: 0.1% neomycin sulfate (NE), 0.1% streptomycin sulfate (ST) or 0.1% penicillin G potassium (PE). The hypocholesterolemic effect of BF was observed only in rats fed the diet supplemented with NE, but not in rats fed the diets supplemented with ST or PE. Cecal acetate and n-butyrate concentrations together with fecal bile acid excretion, were higher in rats fed the 10% BF diet than in those fed the FF diet. The BF-induced increase in cecal short-chain fatty acids and bile acid excretion were smaller in rats with NE and ST in their diet compared with those with PE in their diet. These results suggest that the fermentation of BF by NE-insensitive bacteria and ST-and PE-sensitive bacteria, may be related to the hypocholesterolemic effect of BF. Cecal infusion of three fractions prepared from cecal contents (water-soluble, ether-chloroform-soluble and residues) of BF-fed rats did not cause any reduction in plasma cholesterol concentration in rats fed the FF diet.
