Dietary N-3 polyunsaturated fatty acids decrease biliary cholesterol saturation in gallstone disease

Because fatty acid composition of biliary phospholipids influences
cholesterol secretion into bile, we investigated whether
replacement of n-1 monounsaturated or n-6 polyunsaturated fatty
acids with n-3 polyunsaturated fatty acids in biliary
phosphatidylcholines reduces supersaturation with cholesterol and
prevents precipitation of cholesterol crystals in bile of gallstone
patients. Seven patients with radiolucent gallstones in functioning
gallbladders were studied before (control) and after 5 wk of
dietary supplementation with marine fish oil (11.3 gm/day = 3.75 gm
n-3 polyunsaturated fatty acids/day). Duodenal bile was collected
for analysis during intravenous infusion of cholecystokinin.
Gallbladder emptying in response to cholecystokinin was comparable
before and during intake of n-3 polyunsaturated fatty acids. Intake
of n-3 polyunsaturated fatty acids increased (p < 0.001) the
fractions of eicosapentaenoic and docosahexaenoic acids and
decreased the fractions of linoleic (p < 0.001) and arachidonic
acids (p < 0.02) in biliary phospholipids. Concomitantly, the
molar ratio of cholesterol to phospholipids decreased (-19%; p <
0.05). As a consequence, the cholesterol saturation index was
reduced by -25% (p = 0.01), from 1.60 ± 0.44 to 1.24 ± 0.38.
However, in vitro nucleation time of duodenal bile was not
prolonged. The decrease in cholesterol saturation was not
sufficient to prevent nucleation of cholesterol crystals in bile of
gallstone patients. In conclusion, our data suggest that
cholesterol saturation can be influenced by the fatty acid
composition of the phosphatidylcholines secreted in bile.