Serum lipids, biliary lipid composition, and bile acid metabolism in vegetarians as compared to normal controls

Since dietary factors have been implicated in various diseases, such as coronary heart disease, gallstone formation and colonic cancer, possibly by affecting cholesterol and bile acid metabolism, we studied serum lipid levels, biliary lipid composition, cholic acid and deoxycholic acid kinetics in a group of young healthy male vegetarians and in age, sex and weight matched control subjects. Daily intake of nutrients was higher with respect to polyunsaturated fatty acids, carbohydrates and dietary fibre in the vegetarian group. Although mean serum lipid levels in the vegetarian were 8-28% lower than in the control subjects, differences were not statistically significant. Biliary lipid and biliary bile acid composition were similar in both groups. Bile acid kinetics, measured after simultaneous injection of [3H]cholic acid and [14C]deoxycholic acid, showed a slightly lower output of cholic acid and a slightly higher input of deoxycholic acid in the vegetarians, this causing a significantly (P less than 0.025) higher 7 alpha-dehydroxylation fraction (input deoxycholic acid divided by synthesis of cholic acid) in the vegetarians. Our results in young males suggest that bile acid conservation is associated with a vegetarian diet, but do not support the supposition that a vegetarian diet reduces deoxycholate formation.