THE EFFECT OF NONSTARCH POLYSACCHARIDE SUPPLEMENTATION ON CIRCULATINGBILE-ACIDS, HORMONE AND METABOLITE LEVELS FOLLOWING A FAT MEAL IN HUMAN-SUBJECTS

The effects of guar pum, sugar-beet fibre (SBF) and wheat bran supplem entation of a high-fat test meal were compared with an NSP-free contro l meal and a meal containing an equivalent amount of the ion-exchange resin cholestyramine in healthy non-obese human volunteers. Their effe cts on gastric emptying, postprandial circulating bile acids, triacylg lycerols and gastrointestinal hormone levels were studied. The in vitr o binding of NSP and cholestyramine to [1-C-14]glycocholic acid was me asured and compared with their in vivo effect. Guar gum and cholestyra mine supplementation significantly lowered circulating postprandial bi le acid, triacylglycerol and gastric inhibitory polypeptide concentrat ions, but sugar-beet fibre and wheat bran were without effect. Liquid gastric emptying, as assessed by circulating paracetamol levels, was s lightly accelerated in the guar gum-supplemented meal. Glycocholic aci d bound strongly to the insoluble fraction of cholestyramine and the s oluble fraction of guar gum. The insoluble fractions of SBF and wheat bran bound only small quantities of glycocholate; no bile acid binding was detected in the soluble fractions of these NSP. The study demonst rates that measurement of postprandial bile acids enables an indirect measurement to be made of bile acid binding to NSP in vivo. The result s support the hypothesis that the hypocholesterolaemic action of guar gum is largely mediated via interruption of the enterohepatic bile aci d circulation, but indicate that the hypocholesterolaemic action of SB F is mediated by another mechanism.