The effect of chenodeoxycholic acid (CDCA) on cholesterol absorption

The effect of administration of chenodeoxycholic acid (CDCA) on cholesterol absorption has been investigated in 11 volunteers. Five hundred milligrams of cholesterol, 5 μCi of C14 cholesterol, and 10 μCi of H3 sitosterol (as a nonabsorbable marker) were given with a standard meal. Feces were collected for 6 days and cholesterol absorption was estimated from the recovered C14 radioactivity. The study was repeated after 20 days of treatment with CDCA. Cholesterol saturation of bile and biliary bile acid composition were also studied. Percent CDCA in bile was 40.5 ± 14.0 SDM before treatment and rose to 75.3 ± 5.7 after treatment. Saturation index fell from 1.08 ± 0.31 to 0.71 ± 0.19. Cholesterol absorption was 33.2 ± 11.0% of the administered dose in basal conditions and decreased to 14.9 ± 9.7% after treatment (P < 0.01). In all but 1 subject, CDCA administration was associated with a decreased intestinal transit time. In conclusion, in doses effective to desaturate bile, CDCA seems to decrease dietary cholesterol absorption. This effect could contribute to the desaturation of bile observed during treatment with this bile acid for dissolving gallstones.