Dietary purified oat β-glucan reduces peak glucose absorption and portal insulin release in portal-vein catheterized grower pigs

Kinetics of glucose absorption may affect insulin secretion into the portal vein. The role of wet-fractionated oat β-glucan on these variables is unknown; Thus, the objective was to measure effects of oat β-glucan on glucose absorption and portal insulin release in portal-arterial catheterized grower pigs. A total of three female pigs (35 to 40 kg BW) were catheterized in the portal vein and carotid artery using modified polyvinyl tube catheters. Pigs were fed 3 diets containing 0, 3, or 6% purified β-glucan for 7-d in a repeated 3×3 Latin square. Blood samples were collected from pigs 1 d every wk for 6 wk in heparinized tubes from the carotid artery and portal vein. Blood was collected every 15 min from −15 to 60 min, then every 30 min to 240 min, then every 60 min to 480 min, and 600 min and 720 min postprandially; blood flow was measured simultaneously. Net glucose absorption rate was calculated from plasma portal-arterial differences x flow.

Blood flow increased (P<0.001) after feeding, without a diet effect. Postprandially, β-glucan reduced (P<0.05) net glucose absorption during the first h by 22 to 51%. At 30 and 90 min postprandially, β-glucan decreased (P<0.05) portal release of C-peptide but did not affect portal insulin at 30 min, indicating that β-glucan reduces peak insulin release while maintaining prehepatic insulin homeostasis.

In conclusion, oat β-glucan as a soluble, viscous fibre decreases rate of glucose absorption and peak insulin release in portal vein.