Influence of semisynthetic diet and type of fat on the turnover of deoxycholic acid in the rabbit*

The half-life, pool size, and daily synthesis of deoxycholic acid in ten rabbits were 7.0 days, 752 mg, and 75.8 mg, respectively, on the control diet; and 24.1 days, 1010 mg, and 30.2 mg, respectively, on a semi-synthetic diet containing hydrogenated coconut oil. Corresponding values in eight rabbits on a diet in which the hydrogenated coconut oil was replaced by corn oil were 26.9 days, 1164 mg, and 30.6 mg, respectively, compared to 8.0 days, 910 mg, and 85.0 mg during the control period. The marked drop in serum cholesterol level that occurred when the dietary coconut oil was replaced by corn oil was not accompanied by an increased bile acid synthesis or excretion. The fecal excretion of bile acids was reduced in rabbits fed the semisynthetic diets, whereas the urinary excretion was the same as on the control diet. Urinary elimination corresponded to about 24% of the daily synthesis of deoxycholic acid in rabbits fed the semisynthetic diets. The concentration of bile acids in blood was calculated to be 1.15-3.04 mg/100 m1 of whole blood in four rabbits fed the hydrogenated coconut oil diet, and 0.33-2.02 mg in four rabbits fed the corn oil diet. I%y using a gas-liquid chromatographic technique, a preliminary survey of the fecal sterols and bile acids in rabbits fed different diets was made. The dietary effects on bile acid metabolism are discussed, and it is concluded that the turnover of bile acids in rabbits is the same whether hydrogenated coconut oil or corn oil is fed.