Effects of dietary polyunsaturated and saturated fats on lipoproteins in the baboon

The effects of 2 different dietary fats (40% of calories from corn oil or coconut oil), in the presence of high-dietary cholesterol (1.7 mg/kcal), on the lipoprotein profiles of baboons (Papio cynocephalus sp) were studied by analytic ultracentrifugation, gradient gel electrophoresis (GGE), and heparin-manganese chloride precipitation. Relative to the corn oil (polyunsaturated fat) diet, the coconut oil (saturated fat) diet significantly increased total serum cholesterol by 43% (P < 0.001) by increasing non-precipitable cholesterol (HDL-C) 58% (P < 0.001) and precipitable cholesterol (VLDL + LDL-C) 35% of (P < 0.001). Analytic ultracentrifugal observations indicated that the increase in HDL-C was due to considerable increases in both HDL-I (baboon HDL of size 100-125 Å and hydrated density 1.063-1.120 g/ml) and F_1.20⁰ 9-28 lipoproteins (material of size 125-220 Å and hydrated density 1.03-1.08 g/ml, and containing HDL apolipoproteins and apo E). Concentrations of other HDL subpopulations were unaffected by the dietary saturated rat. The increase in VLDL + LDL-C was due to increased LDL (S_F⁰ 5-12), and to some extent, F of the F_1.20⁰ 9-28 lipoproteins were precipitable by heparin-manganese. In contrast, saturated fat (relative to polyunsaturated fat) induced lower concentrations of IDL saturated fat (relative to polyunsaturated fat) induced lower concentrations of IDL (S_F⁰ 12-20) and VLDL (S_F⁰ 20-100). Lipoprotein size distributions by GGE indicated 5 HDL subpopulations and 2 or more LDL subpopulations in the sera of most baboons. The type of dietary fat did not affect the particle size range of each of the the HDL or LDL subpopulations. The results indicate that dietary fat markedly modulates the distribution of cholesterol between apo A-I-containing (HDL and F_1.20⁰ 9-28) and apo B-containing (IDL and VLDL) lipoproteins without altering the presence of subpopulations based on particle size.