EFFECT OF CYCLODEXTRIN ON PLASMA-LIPIDS AND CHOLESTEROL-METABOLISM INTHE RAT

beta-Cyclodextrin (beta-CD) is a bile acid and sterol sequestrant prod uced by enzymatic modification of starch; this product has the potenti al to decrease plasma cholesterol. In contrast to the sequestrants hav ing resin- or saponin-like properties, beta-CD is rapidly broken down by the large intestine microflora. beta-CD effects on cecal fermentati ons and lipid metabolism were thus investigated in rats adapted to sem ipurified diets containing 0%, 2.5%, or 5% beta-CD. in rats fed beta-C D diets, there was an enlargement of the cecum together with a dramati c increase in the cecal concentration of propionic acid (even with the 2.5% level, in moderately acidic pH conditions). Propionic acid produ ced in the cecum was readily absorbed and entirely taken up by the liv er, whereas there was no significant acetic acid uptake. Dietary beta- CD was highly effective in enhancing bile acid entry into to the cecum : the cecal bile acids pool was 2.2- and 3.6-fold enlarged in rats fed the 2.5% and 5% beta-CD diets, respectively. The solubility percentag e of bile acids decreased to approximately 25% in rats fed the beta-CD diets (v 51% in controls); the cecal concentration of soluble bile ac ids was thus relatively low in these animals. The fecal excretion of s teroids was strongly enhanced by beta-CD, and bile acids excretion was practically proportional to the dietary beta-CD level. There was a ne t lipid-lowering effect of beta-CD, even at the 2.5% level. The effect was more pronounced on triglycerides than on cholesterol. Hypocholest erolemia corresponded to a decrease of very-low-density lipoprotein (V LDL), low-density lipoprotein (LDL), and high-density lipoprotein 1 (H DL(1)) cholesterol, whereas HDL(2) cholesterol was unchanged. In paral lel, there was an induction of microsomal hydroxymethyl glutaryl coenz yme A (HMG CoA) reductase, also proportional to the dietary beta-CD le vel. In conclusion, beta-CD appears to be an effective lipid-lowering agent due to its bile acid-sequestrant properties. The production of s hort-chain fatty acids (SCFA) from beta-CD by the large intestine micr oflora probably plays a minor role in its effects on lipid metabolism. Nevertheless, by acidifying the large intestine content and solubiliz ing Ca, cecal SCFA contribute to inhibit the passive reabsorption of b ile acids. Copyright (C) 1995 by W.B. Saunders Company