Guar gum and bile: effects on postprandial gallbladder contraction and on serum bile acids in man.

In a randomized cross-over study, 10 healthy volunteers received a fiber-depleted liquid mixed meal alone and, exactly 7 days apart, a combination with 15 g guar gum. Addition of the dietary fiber inhibited emptying of the gall bladder after 30 min to 7 (5-10) ml instead of 4 (3-6) ml (p less than 0.05) and delayed its refilling. Also the postprandial increase in conjugated serum bile acids was prevented by guar gum. The maximal postprandial blood glucose 30 min after ingestion of the meal was reduced from 120 (117-135) mg/dl to 110 (105-119) mg/dl (p less than or equal to 0.05) by guar gum. Serum insulin levels were unaffected by guar gum.--Our data suggest that the addition of guar gum to meals affects enterohepatic circulation of bile acids as well as digestion of carbohydrates.