Some Parameters of Sterol Metabolism in Man on a Sterol- and Fat-Free Diet

¹ From the Department of Clinical Science, University of Illinois College of Medicine, Chicago, Illinois

The average daily fecal elimination of digitonin-precipitable sterol in 11 subjects on a sterol- and fat-free synthetic diet was 421 mg ± 222 (S.D.) mg/day with 95% confidence limits of 272 mg and 570 mg/day. When expressed in relation to body weight the mean was 5.8 mg/kg/day with 95% confidence limits of 4.4 and 7.2 mg/kg/day. For the seven males the figure was 6.4 mg/kg/day and for the four females 4.5 mg/kg/day. The difference between sexes was not statistically significant. On applying the depletion theory, the average total daily size of the intestinal endogenous sterol pool was calculated as 1400 ± 740 mg/day on zero lipid intake. Of the 1400 mg, 980 mg was reabsorbed or was involved in the enterolymphohemohepatic circulation of sterol. The total capacity of the intestine of our subjects to absorb cholesterol on a low fat diet was 2 gm/day of dietary or exogenous cholesterol plus 0.98 gm/day of endogenous sterol, or 2.98 gm/day. The average total daily synthesis of cholesterol by the body was calculated to be 2100 mg, the amount catabolized being 1680 mg. Assuming that 87% of the cholesterol metabolized is converted to bile acid, then 1460 mg/day of cholesterol is converted to bile acid.