Guar Gum Reduces Postprandial Hypotension in Older People

Objective: To determine whether slowing of gastric emptying and glucose absorption with guar gum would reduce the fall in blood pressure after an oral glucose load in older subjects.

Design: A randomized, experimental, cross-over study.

Setting: Department of Nuclear Medicine, Royal Adelaide Hospital, Adelaide, SA, Australia.

Participants: Ten healthy subjects, age 67 to 78.

Measurements: Simultaneous measurements of gastric emptying, blood pressure, blood glucose, serum insulin, and oral glucose absorption (3-O-methyl-D-glucose [3-OMG]) on two occasions after ingestion of 300 mL water containing 50 g glucose and 30 mL lemon juice, 3 g 3-OMG labeled with 99mTc-sulphur colloid; with or without 9 g guar gum. Blood pressure and gastric emptying were monitored for 180 minutes.

Results: The magnitude of the falls in systolic (P = .02), diastolic (P < .05), and mean arterial (P = .05) blood pressure were less, and gastric emptying slower (P < .05), after guar. Blood glucose, insulin, and 3-OMG concentrations were reduced (P < .001 for all) by guar. 3-OMG concentrations were inversely related to the intragastric retention of glucose (r = -0.72, P = .02) and blood pressure was inversely related to 3-OMG (r = -0.64, P < .05) after the drink without guar. The blood glucose concentration was related to 3-OMG (r > 0.64, P < .05).

Conclusion: Guar gum reduces the magnitude of the fall in blood pressure after oral glucose. Slowing of gastric emptying and glucose absorption may represent a novel approach to the treatment of postprandial hypotension.