Carbohydrate restriction (CR) and dietary cholesterol influence the number of lipoprotein particles and distribution of lipoprotein subfractions in guinea pigs

Abstract

Guinea pigs (n=10) were randomly assigned to 3 different groups: 42% energy from carbohydrate (CHO) and 0.04% cholesterol (control), 42% CHO and 0.25% cholesterol (HCHO) or 11% energy from CHO and 0.25% cholesterol (CR) for 12 wk. Plasma lipids were evaluated and lipoprotein subclasses and size were analyzed by nuclear magnetic resonance. There were no differences in VLDL, LDL or HDL cholesterol or triglyceride concentrations between the CR and the HCHO groups; however all these plasma lipids were higher compared to the control group (P < 0.0001). High CHOL (HCHO and CR groups) resulted in larger VLDL particles (71.1 ± 6.9, 78.9 ± 3.33 nm, respectively) compared to control (44.3 ± 10.8 nm). In addition, there were higher concentrations of the large VLDL (>60nm) and the medium VLDL (> 27 nm) in the high CHOL groups compared to the control (P < 0.001). Similarly the number of HDL particles and the concentration of the medium (>8.2 nm) and small HDL (>7.2 nm) were higher with the high CHOL (P < 0.001). In contrast, CHO restriction significantly affected the size and concentration of LDL particles. Total LDL particles were lower in the CR (291.3 ± 85.0 nmol/L) compared to HCHO group (467.6 ± 113.1 nmol/L). The concentrations of medium LDL (> 19.8 nm) and small LDL (>18 nm) were lower in the CR group (98.4 ± 90.8 and 29.3 ± 24.9 nmol/L, respectively) than in the HCHO group (261.8 ± 105.8 and 64.9 ± 27.9 nmol/L, respectively) (P < 0.0001). These results indicate that CHOL increased the atherogenicity of both VLDL and HDL while CR decreased the number of LDL particles, specifically the more atherogenic smaller LDL.