Objective: To compare the effect of a high monounsaturated fatty acid (MUFA) diet and of a control low-fat diet consumed under ad libitum conditions on plasma apolipoprotein (apo) C-III metabolism. Design: Randomized, two-arm parallel dietary trial. Setting: Diets were prepared and consumed at the metabolic kitchen of the Department of Food Sciences and Nutrition, and laboratory analyses were performed at the Institute of Nutraceuticals and Functional Foods at Laval University. Subjects and interventions: Eighteen men were randomly assigned to either the high MUFA diet or the low-fat control diet, which they consumed for 6-7 weeks. Before and after the dietary intervention, subjects received a primed-constant infusion of [5,5,5-D 3 ]-L-leucine for 12 h under constant feeding conditions for the determination of plasma apoC-III kinetics. Results: The high-MUFA diet and the low-fat control diet had no significant impact on plasma apoC-III production rate (PR) or fractional catabolic rate. However, diet-induced variations in plasma apoCIII PR predicted the reduction in plasma triglycerides and apoC-III levels (r ¼ 0.85, Po0.01 and r ¼ 0.73, Po0.05, respectively) in the high MUFA group only. Conclusions: These results suggest that the hypotriglyceridemic effect of a high-MUFA diet may be attributable in part to a reduced hepatic production of apoC-III.

Objective: The aim of the present study was to investigate the combined impact of visceral adipose tissue (VAT) and secretory group IIA phospholipase A 2 (sPLA 2 -IIA) concentrations on the atherogenicity of low-density lipoprotein (LDL) particles among men. Subjects: Analyses were conducted in 74 mid-obese healthy men (age: (mean7s.d.) 37.9711.7 years). Methods: Plasma levels of sPLA 2 -IIA were measured with a commercial ELISA and VAT levels were assessed by computed tomography. Distinct subpopulations of LDL particles were characterized from whole plasma using nondenaturating 2-16% gradient gel electrophoresis. Results: Data indicated that plasma sPLA 2 -IIA levels were approximately 29% (P ¼ 0.007) higher among men characterized by a higher accumulation of VAT (4142 vs p142 cm 2 ). Men having high plasma sPLA 2 -IIA levels (X127.2 ng/dl, the median value), were characterized by higher levels of plasma cholesterol (C) and apolipoprotein (apo) B, LDL-C, LDL-apoB, oxidized LDL (OxLDL) and by smaller LDL particles compared to men with sPLA 2 -IIAo127.2 ng/dl. Multiple regression analyses showed that plasma triglycerides and sPLA 2 -IIA levels explained 22.7 and 11.8% of the variance in LDL peak particle size, respectively. Levels of VAT and of sPLA 2 -IIA were the strongest correlates of OxLDL levels explaining, respectively, 15.0 and 5.5% of their variability. Conclusion: Both VAT and sPLA 2 -IIA levels modulate the atherogenecity of LDL by accounting for the reduction in their size and their susceptibility to oxidation.