INVOLVEMENT OF SMALL-INTESTINAL MOTILITY IN BLOOD-GLUCOSE RESPONSE TO DIETARY FIBER IN MAN

Three dietary fibres with different physicochemical properties were studied in healthy humans for their effects on small intestinal motility and postprandial hyperglycaemia. Duodeno-jejunal motor activity was evaluated electromyographically for 180 min in six subjects who had ingested a test meal composed of glucose alone or glucose with 15 g of wheat bran (WB), sugar beet (SB) or ispaghula (I) fibres. Glucose and insulin concentrations were determined during the same period. Each subject received each of the four test meals randomly during a 4 d period. Addition of SB or I to the glucose meal altered duodeno-jejunal motility. Both of these fibres inhibited stationary contractile activity and increased the propagation length and velocity of propagated activity, whereas addition of WB had no effect. These results could reflect the high water-holding capacity of SB and I. Blood glycaemic response to the glucose meal was reduced by SB and I but remained unchanged with WB. Postprandial blood glucose levels were significantly correlated with the total motility index (r 0.82) and stationary activity (r 0.79). Taken together, these observations suggest that the contractile activity induced by dietary fibre in the small intestine probably plays a major role in delayed glucose absorption.