The enterohepatic circulation of bile acids as they relate to lipid disorders.

Bile acids' play a fundamental role in lipid metabolism. They solubilize the products of lipolysis thereby facilitating digestion of triglycerides and the absorption of monoglycerides and fatty acids, and their presence is mandatory for the absorption of cholesterol and the fat-soluble vitamins. The enterohepatic circulation of bile acids ensures that adequate concentrations of these biological detergents are available when needed in the intestinal lumen. This paper, therefore, begins by reviewing the normal enterohepatic circulation of bile acids as illustrated by studies in the rhesus monkey. The influence of diet and particularly of dietary fat on this circulation is then discussed with emphasis on some further recent studies in the monkey which suggest a possible mechanism for the hypocholesterolaemic action of polyunsaturated fats. Finally, some effects of interrupting the bile acid enterohepatic circulation are considered. These include the development of hyperoxaluria and occasionally renal oxalate stone formation, and the formation of a bile supersaturated with cholesterol and the subsequent development of cholesterol gallstones.