HDL-subpopulation patterns in response to reductions in dietary total and saturated fat intakes in healthy subjects

Background: Little information is available about HDL subpopulations during dietary changes. Objective: The objective was to investigate the effect of reductions in total and saturated fat intakes on HDL subpopulations. Design: Multiracial, young and elderly men and women (n = 103) participating in the double-blind, randomized DELTA (Dietary Effects on Lipoproteins and Thrombogenic Activities) Study consumed 3 different diets, each for 8 wk: an average American diet (AAD: 34.3% total fat, 15.0% saturated fat), the American Heart Association Step I diet (28.6% total fat, 9.0% saturated fat), and a diet low in saturated fat (25.3% total fat, 6.1% saturated fat). Results: HDL₂-cholesterol concentrations, by differential precipitation, decreased (P < 0.001) in a stepwise fashion after the reduction of total and saturated fat: 0.58 ± 0.21, 0.53 ± 0.19, and 0.48 ± 0.18 mmol/L with the AAD, Step I, and low-fat diets, respectively. HDL₃ cholesterol decreased (P < 0.01) less: 0.76 ± 0.13, 0.73 ± 0.12, and 0.72 ± 0.11 mmol/L with the AAD, Step I, and low-fat diets, respectively. As measured by nondenaturing gradient gel electrophoresis, the larger-size HDL(2b) subpopulation decreased with the reduction in dietary fat, and a corresponding relative increase was seen for the smaller-sized HDL(3a, 3b), and (3c) subpopulations (P < 0.01). HDL₂-cholesterol concentrations correlated negatively with serum triacylglycerol concentrations on all 3 diets: r = -0.46, -0.37, and -0.45 with the AAD, Step I, and low-fat diets, respectively (P < 0.0001). A similar negative correlation was seen for HDL(2b), whereas HDL(3a, 3b,) and (3c) correlated positively with triacylglycerol concentrations. Diet-induced changes in serum triacylglycerol were negatively correlated with changes in HDL₂ and HDL(2b) cholesterol. Conclusions: A reduction in dietary total and saturated fat decreased both large (HDL₂ and HDL(2b)) and small, dense HDL subpopulations, although decreases in HDL₂ and HDL(2b) were most pronounced.