Effect of the selective expansion of cholic acid pool on bile lipid composition: Possible mechanism of bile acid induced biliary cholesterol desaturation

Abstract The effect of cholic acid pool expansion on biliary lipid composition was investigated in 21 subjects with cholesterol gallstones. All subjects were fed cholic acid (15 mg/kg/day) and ampicillin (2 g/day) in order to depress the intestinal degradation of cholic to deoxycholic acid. Five additional subjects were given ampicillin alone. The treatment lasted 2–3 wk. Parameters investigated included biliary and plasma lipid, biliary bile acid composition, and total and individual bile acid pool size. In 11 of 21 subjects (group I) cholic acid pool expanded two-threefold, whereas deoxycholic acid pool increased only slightly. In this group mean saturation index fell from 1.32 ± 0.27 (mean ± SD) to 0.93 ± 0.25 (p