Effects of dietary cholesterol on cholesterol and bile acid homeostasis in patients with cholesterol gallstones

Abstract

We examined changes in cholesterol and bile acid metabolism produced by dietary cholesterol in gallstone subjects and matched controls. Healthy women were recruited and, after confirming the presence or absence of radiolucent gallstones, they were studied on regular diets and again on the same diet supplemented with five eggs daily for 15-18 d. Studies included plasma lipids, lipoproteins and apolipoproteins, dietary records, cholesterol absorption, cholesterol synthesis, plasma clearance of chylomicron remnants, biliary lipid composition, and secretion and bile acid kinetics. On low cholesterol, gallstone subjects absorbed a slightly lower fraction of dietary cholesterol, synthesized more cholesterol, and had smaller bile acid pools and faster fractional turnover rate (FTR) of bile acids. On high cholesterol, the fraction of cholesterol absorbed decreased in both groups and cholesterol synthesis decreased, especially in the gallstone group. Biliary cholesterol secretion increased in the gallstone group only. FTR of bile acids did not change in either group. Bile acid synthesis and pool tended to increase (P = NS) in the controls, but in gallstone subjects, synthesis and pool size decreased. We concluded that in gallstone subjects cholesterol and bile acid homeostasis is significantly altered, and that increasing dietary cholesterol increases biliary cholesterol secretion and decreases bile acid synthesis and pool, changes associated with cholesterol gallstone formation.