The separate effects contributed by
dietary cholesterol and
dietary fat on several parameters of biliary lipid metabolism thought to be important in the genesis of
cholesterol gallstones were examined in squirrel and cebus monkeys fed diets containing either corn or
coconut oil from birth. Half the monkeys were also fed
cholesterol. In
gallstone-susceptible squirrel monkeys,
corn oil tended to decrease the
bile acid pool size and decrease the percentage of
taurochenodeoxycholic acid.
Dietary cholesterol effected major changes in gallbladder bile molar percent
lipid composition with significantly increased
cholesterol saturation indices that exceeded the metastable-labile limits. The supersaturated biles notwithstanding, none of the monkeys developed
gallstones and only one had
cholesterol crystals in its bile. By contrast, the
gallstone-resistant cebus monkeys experienced less remarkable shifts in biliary
lipid composition during dietary challenges of
cholesterol and fat. The data are consistent with the hypothesis that neither a diminished
bile acid pool size nor bile supersaturated with
cholesterol are sufficient in themselves to result in
gallstone formation in immature monkeys.