The possible role of free fatty acids in the pathogenesis of cholesterol gallstones in man

The lipid composition of hepatic and gallbladder bile was examined in 20 patients with cholesterol gallstones and in 20 control subjects. Lipid fractions other than bile salts, phospholipids and cholesterol were found to be present, i.e., sterol esters, non-identified fractions and, above all, free fatty acids. The latter probably originated from biliary phospholipids via activity of phospholipases, present in the gallbladder wall. No significant difference in amount and pattern of free fatty acids and phospholipids was found in hepatic bile between patients with gallstones and controls. On the contrary, we observed relevant differences in the lipid composition of gallbladder bile. In this way, we consider that the bile becomes lithogenic inside the gallbladder as a consequence of release of free fatty acids, particularly if these are constituted by saturated chains. In fact, these can compete with cholesterol in the solubilization in biliary micelles. On the other hand, free fatty acids can be directly toxic for the gallbladder wall and produce a cholecystitis.