Lipid Metabolism Responses in Rats Fed Docosahexaenoic Acid Given as Monoacylglycerol, Diacylglycerol, Triacylglycerol, and Ethyl Ester

Abstract

We examined the effects of the dietary docosahexaenoic acid (DHA), given as monoacylglycerol (MG), diacylglycerol (DG), triacylglycerol (TG) and ethyl ester (EE), on plasma and liver lipid profiles in rats. Male Sprague-Dawley rats were fed semi purified diets containing 10% fat with a constant polyunsaturated/monounsaturated/saturated fatty acid ratio for 1 week. One% of DHA-MG, DG, TG and EE were added to the rat’s diets as a substitute for fat. Control rats were fed a fat containing linoleic acid as a sole polyunsaturated fatty acid. The apparent absorption rates of the total fat and DHA were almost quantitative (>95%) in all groups. The plasma concentrations of total and HDL cholesterol in the four DHA-supplemented groups were significantly lower than in the control group. DHA-DG and TG were more effective for lowering plasma total cholesterol concentration than DHA-MG. Also, DHA-DG was more effective than DHA-EE. The plasma TG concentration was significantly lower only in the DHA-DG and TG groups than in the control group, while this effect was more pronounced in DHA-TG than in DHA-DG. DHA feeding increased the proportion of n-3 fatty acids accompanying a complementary decrease of arachidonic acid in liver lipid fractions. The percentages of total n-3 fatty acids were significantly higher in the DHA-TG group than in other DHA groups in liver total lipids. These results suggest that the structural differences of DHA-containing lipids in dietary fats affected lipid metabolism differently in rats, and the DHA-DG and TG more effectively reduced plasma lipids than DHA-MG and EE.