Effects of dietary monounsaturated fatty acids on lipoprotein concentrations, compositions, and subfraction distributions and on VLDL apolipoprotein B kinetics: dose-dependent effects on LDL
2003
Gill, Jason M.R. | Brown, Jacqueline C. | Caslake, Muriel J. | Wright, Dawn M. | Cooney, Josephine | Bedford, Dorothy | Hughes, David A. | Stanley, John C. | Packard, Chris J.
Background: Replacing dietary saturated fatty acids (SFAs) with monounsaturated fatty acids (MUFAs) lowers LDL cholesterol, but the underlying mechanisms remain unclear. Objective: We assessed the effects of replacing dietary SFAs with MUFAs on concentrations and subclass distributions of VLDL, intermediate-density lipoprotein, LDL, and HDL and on VLDL apolipoprotein B kinetics. Design: Thirty-five moderately hypercholesterolemic, middle-aged volunteers consumed for 6 wk, in random order, diets containing low (L-MUFA; 7.8% of energy from MUFAs), moderate (M-MUFA; 10.3% from MUFAs), or high (H-MUFA; 13.7% from MUFAs) amounts of MUFAs. Fasting blood samples were taken from all subjects after each intervention. VLDL apolipoprotein B kinetic studies were performed in a subgroup after the L-MUFA and H-MUFA diets. Results: Plasma cholesterol concentrations decreased in a dose-dependent manner with increasing intakes of dietary MUFAs. This change was entirely accounted for by reduced LDL cholesterol (-0.20 and -0.49 mmol/L after the M-MUFA and H-MUFA diets, respectively, compared with the concentration after the L-MUFA diet; P for trend < 0.01). Plasma triacylglycerol and HDL cholesterol were not significantly affected by the dietary intervention, nor were the concentrations of VLDL1 (Sf 60-400), VLDL2 (Sf 20-60), or intermediate-density lipoprotein (Sf 12-20). Production and catabolic rates for VLDL1 and VLDL2 were also unaffected. HDL and LDL subclass distributions were not significantly altered, but as a consequence of the overall LDL lowering, concentrations of atherogenic LDL-III were 25% lower after the H-MUFA diet than after the L-MUFA diet (P = 0.02). Conclusion: The effects of replacing dietary SFAs with MUFAs on lipoprotein metabolism appear to be almost exclusively limited to the LDL density class.
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