Sterol composition of normal human bile. Effects of feeding shellfish (marine) sterols.

To examine the sterol composition of normal human bile and the effects of dietary components from certain shellfish upon bile composition, we fed 7 subjects diets rich in shellfish for 2 wk following a typical American diet. The total cholesterol, bile acid, and phospholipid, and the individual sterols and bile acids of the bile samples during each dietary period were measured. In the bile of 7 subjects consuming the typical American diet, nine different neutral sterols, in addition to cholesterol, were identified. Similar patterns of these sterols have been found in human gallstones and in plasma after shellfish feeding. The five shellfish sterols (22-dehydrocholesterol, 24-methylene cholesterol, brassicasterol, isofucosterol, and a C-26 sterol) increased from 0.3% to a total of 5.2% (p less than 0.001) of total sterols. A comparison of the ratios of various shellfish sterols to cholesterol in plasma and in bile suggested selectively greater excretion of shellfish sterols relative to cholesterol. Our data demonstrated that human bile contains a mixture of sterols and that its sterol composition can be readily altered by dietary changes. The lithogenicity of the bile based on the ratio of cholesterol, bile acids, and phospholipids, and the bile acid composition was not affected by the presence of shellfish sterols. However, since some of these sterols occur in human gallstones, their lithogenic capacity cannot be ruled out.