Evaluation of a continuous isotope feeding method for measurement of cholesterol absorption in man

A new method has been developed for measurement of cholesterol absorption. Seven patients were fed [14C]cholesterol together with [3H]-beta-sitosterol three times daily for 10 days. Stools were collected on days 3--10. The ratio of isotopes in stools became essentially constant after the first 3 days of isotope administration. Percentage absorption of cholesterol was calculated from the difference between the dietary and fecal isotope ratios. Percentage absorption of cholesterol in these seven patients ranged from 47 to 65% (mean 54%). The coefficient of variation on individual samples for all the patients ranged from 3.2 to 15.0% (mean 7.8%). This method was evaluated in five additional patients by comparison with a standard sterol balance method (Method II, see Quintao, E., S. M. Grundy, and E. H. Ahrens. 1971. J. Lipid Res. 12: 221--232). The results obtained by the two methods were essentially identical. The new method offers the advantages of simplicity of administration of isotope, ease of analysis of stool samples, and daily repeatability of analysis.