Intestinal cholesterol can be absorbed by the host or converted by the intestinal microbiota. The main metabolite of cholesterol conversion is coprostanol, which is unabsorbable. The aim of the present study was to examine the intestinal microbial conversion of cholesterol to coprostanol in healthy subjects. Cholesterol and coprostanol were determined in faecal samples from individuals living in Norway, Scotland and Sweden and examined for possible relationship to age (<36 years, 36-50 years and >50 years old) and gender. The results were expressed as the percentage of coprostanol in the total amount of cholesterol plus coprostanol (coprostanol%). For purposes of classification, subjects were divided in nonconverters (<5% conversion rate), low converters (between 5% and <40% conversion rate) and high converters (at least 40% conversion rate). Thus, faecal samples from 633 healthy individuals were examined. As no differences between countries were observed, the data were pooled. Overall, in the male group, a higher percentage of non-converters was observed in the youngest group compared with the two other age groups (17% compared with 7% and 2% in the two other age groups, respectively, p<0.05), whereas the percentage of high converters was increased in the oldest age group compared with the other age groups (84% vs 62% and 60%, respectively, p<0.05). In females, the percentage of converters was of the same order of magnitude in all age groups. We report a reduction in the number of non-converters and low converters of intestinal cholesterol to coprostanol in the oldest male group. We hypothesize that the observed alterations in the male group correspond to a loss of healthy subjects (by disease or death) among the non-converters and low converters.