Stone formation in Gall bladder is enhanced by all expect -

Vagal stimulation increases gall bladder motility and thus prevents stone formation. As described in the previous question Clofibrate - increases biliary cholesterol Cholestyramine and ilea' resection-decrease enterohepatic circulation of bile salts. thus they predispose to cholesterol stone formation. Also know Earlier it was thought that truncal vagotomy increased the risk of cholesterol gall stone formation. But recent studies show no increased incidence of gall stone formation following truncal vagotomy. Ref : Bailey 23rd/e p. 975