In vitro study of possible role of dietary fiber in lowering postprandial serum glucose

There have been many reports concerning the role of dietary fiber in loweri ng postprandial serum glucose, and the main mechanism was regarded as the v iscosity of different dietary fibers in hampering diffusion of glucose and postponing absorption and digestion of carbohydrates. In this paper, two ki nds of water-insoluble dietary fibers, water-insoluble dietary fiber of whe at bran and enzyme-resistant starch of maize amylose, and four kinds of wat er-soluble dietary fibers, water-soluble dietary fiber of wheat bran, carbo xymethyl cellulose, guar gum, and xanthan gum, were used to investigate the ir postprandial serum glucose lowering mechanism in vitro. The results show ed that these dietary fibers lowered postprandial serum glucose levels at l east by three mechanisms. First, dietary fibers increase the viscosity of s mall intestine juice and hinder diffusion of glucose; second, they bind glu cose and decrease the concentration of available glucose in the small intes tine; and, third, they retard a-amylase action through capsuling starch and the enzyme and might directly inhibit the enzyme. All of these decreased t he absorption rate of glucose and the concentration of postprandial serum g lucose.