Effect of Wheat Bran on Cholesterol Metabolism in Rats

Abstract

Purified wheat bran (PWB) was prepared from wheat bran (WB) by washing with water and ethanol. The hemicellulose-A fraction (HC-A) and the hemicellulose-B fraction (HC-B) were extracted from WB with alkaline solution. The hypocholesterolemic effects of WB, PWB, HC-A and HC-B were examined in rats fed on a hypercholesterolemic diet containing 1% cholesterol and 0.25% sodium cholate. PWB, HC-A and HC-B significantly prevented the elevation of serum cholesterol level in comparision with WB. HC-B, which is water-soluble, had a more significant effect than HC-A, which is water-insoluble. No remarkable change in gastrointestinal transit time was observed between WB and PWB. Therefore, there was no relationship between the cholesterolemic effect and gastrointestinal transit time. Scanning electron microscopy and sugar component analysis of WB and PWB residues collected from each gastrointestinal tract indicated that the amount of non-cellulosic polysaccharide (hemicellulose) released from the PWB cell wall was significantly larger than that from the WB cell wall. From these results, it was considered that a soluble substance contributed to the hypocholesterolemic effect.