Effect of fat intake on cholesterol turnover and bile acid formation.

Abstract

SummaryThree groups of male rats were maintained on diets con taining different amounts of fat. After one week on such regimens, they were injected intraperitoneally with cholesterol-3H. During the following 28 days, the radioactivity and quantity of fecal cholesterol and its metabolites were determined. The coprostanol excretion was the about same in all groups and the bile acids excretion increased with increasing fat intake; however, compared to the fat-free group, the excretion of the injected cholesterol-3H was greater in the 3% fat group and less in the 10% fat group. Consequently, the specific radioactivity of bile acids was lower in the 10% group than in the others. The half life of labelled cholesterol was 12.6, 16.0 and 22.2 days for the 3%,10% fat and fat-free groups, respectively. Rather than a fat-free diet, a low fat diet of 3% or so, would be of more advantage in eliminating choleste rol by increasing the formation of bile acids to emulsify the fat. In the 10% fat group, however, the enlarged pool size of bile acid probably delayed cholesterol metabolism to bile acids.The influence of fat feeding on cholesterol metabolism has been reported by many investigators. The absorption of cholesterol increases with the amount of fat intake with an upper limit (1), although the fatty acid composition of the carrier fat affects the extent of sterol absorption (2). Several workers have re ported that fat influenced the biosynthesis and excretion of cholesterol, but with conflicting results. In the experiments of SABINE et al. (3) and JANSEN et al. (4) with mice, the high-fat diet suppressed cholesterol synthesis; whereas with rats, HILL et al. (5,6), using similar diets, found an increase in hepatic synthesis of cholesterol from acetate after feeding fat. BORTZ (7) also observed that fat feed ing to rats maintained on a fat-free diet brought about a decrease in fatty acid synthesis and an increase in cholesterol synthesis. Further, the composition of fatty acids such as linoleate, may influence cholesterol metabolism. (8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19). We found that linoleate had no effect on the half-life of cholesterol, though it lowered plasma cholesterol (20).On the other hand, the relation between the amount of fat intake and chole sterol metabolism is not so clear. Bile acids, the metabolites of cholesterol, are necessary for the digestion and absorption of fat, so fat intake may accelerate the metabolism of cholesterol. The present experiments were therefore designed to examine the effects of varied amounts of dietary fat on overall cholesterol metabolism, using fat with a balanced composition of fatty acids.

Identification of Potential Biomarkers for Gut Barrier Failure in Broiler Chickens

“…Bile acids are synthesized by the liver and released into the lumen of the small intestine via bile, and the majority of bile acids are recovered in the distal end of the small intestine and then returned to the liver for reuse ( 102 ). Bile acid has emerged as important biological molecules that emulsify lipids and liposoluble dietary nutrients to facilitate their digestion and absorption ( 103 , 104 ). It has strong anti-microbial activity and therefore is emerging as a host factor that regulates the composition of microbiota in the gut ( 105 , 106 ).…”