Diet, nutrition intake, and metabolism in populations at high and low risk for colon cancer. Metabolism of neutral sterols.

Cholesterol and its metabolites, together with bile acids, are implicated as risk factors in the genesis and progression of colon cancer. This study was designed to determine differences in the neutral sterol composition of stools from four different population groups differing in their dietary habits as well as in their expected rates for colon cancer. Four study groups consisting of 18 Seventh-day Adventist (SDA) pure vegetarians, 50 SDA lacto-ovo vegetarians, 50 SDA nonvegetarians, and 50 general population nonvegetarians were selected from the greater Los Angeles Basin area. Three-day composite stool samples were lyophilized and then analyzed for their neutral sterol composition. Cholesterol excretion values consistently showed an age-dependent peak in 46- to 50-yr age group for the total population, SDA lacto-ovo vegetarian and SDA-nonvegetarian subgroups being the principal contributors to this age-dependent phenomenon. The SDA pure vegetarians exhibited the lowest fecal concentrations and daily excretion of cholesterol as expected since their intake of dietary cholesterol is insignificant. Among the other SDA, regardless of whether they are lacto-ovo vegetarians or nonvegetarians, their cholesterol excretion patterns were similar but higher than in the nonvegetarians from the general population. Since dietary intakes of cholesterol are not significantly different among the two nonvegetarian groups, the differences in excretion values are attributable to differences in colonic metabolism. The ratio of cholesterol/cholesterol metabolites showed generally lower values among nonvegetarians compared to the matched group of lacto-ovo vegetarians. The observation was made that fecal cholesterol and its metabolites tend to be higher among nonvegetarians compared to those in the corresponding vegetarian groups.