FERMENTABLE CARBOHYDRATES EXERT A MORE POTENT CHOLESTEROL-LOWERING EFFECT THAN CHOLESTYRAMINE

The purpose of this work was to assess the respective role of bile aci d excretion and of the end-products of cecal fermentations in the chol esterol-lowering effect of complex carbohydrates. The effects of two d ifferent fermentable carbohydrates (guar gum, beta-cyclodextrin), and sequestrant resin (cholestyramine) have been investigated in male Wist ar rats. Guar gum and beta-cyclodextrin are broken down in the large b owel, with fermentation rich in propionic acid (37% against 26% for co ntrol), whereas cholestyramine did not enhance cecal fermentations. be ta-Cyclodextrin and guar gum were less potent than cholestyramine to e nhance bile acids and sterol excretion. Nevertheless, fermentable carb ohydrates exerted a more potent cholesterol-lowering effect than chole styramine. beta-Cyclodextrin also depressed triacylglycerol-rich lipop rotein (TGRLP). Fermentable carbohydrates lowered cholesterol of LDL a nd HDL1 fractions. The induction of hepatic HMG-CoA reductase was prac tically proportional to rate of fecal steroid excretion. Moreover, wit h beta-cyclodextrin, hepatic HMG-CoA reductase induction was concomita nt to a decrease in fatty acid synthase (FAS) activity. Thus, the chol esterol-lowering effect of fermentable carbohydrates could be related to a depressed lipogenesis, as well as to an accelerated removal of HD L1, in relation to an elevated hepatic demand of cholesterol. In concl usion, fermentable carbohydrates could favour cholesterol elimination and have a general lipid-lowering effect by exerting more complex phys iological effects than cholestyramine.