Alteration of high density lipoprotein subfractions of nonhuman primates fed fish-oil diets. Selective lowering of HDL subfractions of intermediate size and density.

Abstract

Two groups of adult male African green grivet monkeys (12 animals in each group) were fed atherogenic diets containing 40% of total calories as fat with half of the fat calories derived from lard or menhaden oil and 0.8 mg cholesterol/kcal for a period of 10 months to ascertain the effect of such diets on lipoprotein concentrations, composition, and distribution. After 8 months on this diet, the animals' lipoproteins were isolated from their plasma by ultracentrifugation and agarose column chromatography, and these were characterized chemically. Compared with the lard-fed group, the menhaden oil-fed animals had significantly lower total plasma cholesterol (decreases 33%), HDL cholesterol (decreases 33%) and apo A-I (decreases 30%) concentrations and LDL molecular weights (decreases 15%). Although the fish-oil diets resulted in an average similar reduction of LDL cholesterol concentrations (decreases 34%), the decrease was not statistically significant. The lipid and apoprotein compositions of plasma LDL and HDL were similar between the two groups of animals. The distribution of HDL subfractions was determined by gradient gel electrophoresis and density gradient ultracentrifugation. The fish-oil group had a significant reduction in protein (decreases 46%) of HDL subfractions of intermediate size (80 to 88 A) compared to the lard-fed group. By density gradient ultracentrifugation, there was a 35% to 40% lower concentration of protein in the d = 1.10-1.13 g/ml subfraction of fish-oil-fed monkeys. Thus, feeding fish oil to nonhuman primates results in a selective decrease in the concentration of HDL subfractions of intermediate size and density compared to lard-fed animals.(ABSTRACT TRUNCATED AT 250 WORDS)