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 tot al and saturated fat intakes on HDL subpopulations. Design: Multiracial, young and elderly men and women (n = 103) participatin g in the double-blind, randomized DELTA (Dietary Effects on Lipoproteins an d 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 A merican 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, de creased (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 decrease d (P < 0.01) less: 0.76 +/- 0.13, 0.73 +/- 0.12, and 0.72 +/- 0.11 mmol/L w ith the AAD, Step I, and low-fat diets, respectively. As measured by nonden aturing gradient gel electrophoresis, the larger-size HDL2b subpopulation d ecreased with the reduction in dietary fat,and a corresponding relative inc rease was seen for the smaller-sized HDL3a, (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 w ith the AAD, Step I, and low-fat diets, respectively (P < 0.0001). A simila r negative correlation was seen for HDL2b, whereas HDL3a, (3b) and (3c) cor related positively with triacylglycerol concentrations. Diet-induced change s in serum triacylglycerol were negatively correlated with changes in HDL2 and HDL2b cholesterol. Conclusions: A reduction in dietary total and saturated fat decreased both large (HDL2 and HDL2b) and small, dense HDL subpopulations, although decrea ses in HDL2 and HDL2b were most pronounced.