EVALUATION OF OAT BRAN AS A SOLUBLE FIBER SOURCE - CHARACTERIZATION OF OAT BETA-GLUCAN AND ITS EFFECTS ON GLYCEMIC RESPONSE

Oat beta-glucan, present in oat bran in greater concentrations than in the whole oat great, is mainly composed of beta-(1 --> 3)-linked cellotriosyl and cellotetraosyl units, present at 52 and 34% by weight of the molecule, respectively, The remaining structure consists of beta-(1 --> 3)-linked blocks composed of four or more consecutive beta-(1 --> 4)-linked D-glucopyranosyl units. Size-exclusion chromatography indicated a molecular weight for oat beta-glucan of 2-3 x 10(6). This was significantly reduced during digestion in the small intestine of rats and chicks. In healthy human volunteers, oat beta-glucan reduced the postprandial glucose response to an oral glucose load similarly to guar gum. The effectiveness of oat beta-glucan was proportional to the logarithm of the viscosity of the solution fed.