Dietary impact on biliary lipids and gallstones.

Although dietary factors influence bile lithogenicity and gallstone formation, the main dietary effect appears to be indirect, depending on an interaction between caloric consumption and gender-specific aspects of lipoprotein metabolism. Excessive energy intake elicits its detrimental effect by altering lipoprotein and hepatic cholesterol metabolism in association with hyperinsulinemia. Factors, dietary and genetic, that favor elevated hepatic cholesterol synthesis and production of a bile acid profile in which chenodeoxycholic acid predominates appear to be associated with lithogenic bile. An inconsistent effect of dietary fat saturation on gallstones is that polyunsaturates possibly increase risk in men and decrease risk in women. Vegetable protein may reduce the risk of cholelithiasis. Whereas both the amount and type of dietary fiber influence cholesterol and bile lipid metabolism, specific associations between fiber and gallstones in humans remain elusive.