Effect of dietary bile acids,cholesterol, and β-sitosterol upon formation of coprostanol and 7-dehydroxylation of bile acids by rat

During studies of sterol metabolism in the rat, the fecal neutral sterol fraction was analyzed by a combination of thin layer chromatography and gas liquid chromatography. On a stock diet of rat chow supplemented with 5% corn oil, the rats excreted 14.5 mg/day of total neutral sterols. Coprostanol comprised 35% (5 mg/day) of this fraction. When the diet was supplemented with 0.5% sodium taurochenodeoxycholate, the amount of coprostanol in the feces remained the same as in the controls (3.2 mg/day, 32%). The addition of 0.5% sodium taurocholate to the diet resulted in a fivefold reduction of coprostanol formation (0.6 mg/day, 8%). When 1.2% cholesterol was added to the stock diet, the amount of coprostanol present in the feces decreased to an average of 11% compared to controls, but the absolute amount formed was greater (35 mg/day). On a diet enriched with 0.8% β-sitosterol, the rats, on the average, converted 23% of the cholesterol to coprostanol. Feeding diets enriched with sodium taurochenodeoxycholate and sodium taurocholate reduced the 7-dehydroxylation of primary bile acids in the feces by 28% and 42%, respectively. The conversion of primary bile acids to secondary bile acids in the feces of control, cholesterol, and β-sitosterol fed rats was the same (64%).