Randomized controlled trial of the effect of n-3 fatty acid supplementation on the metabolism of apolipoprotein B-100 and chylomicron remnants in men with visceral obesity.

BACKGROUND Lipid abnormalities may contribute to the increased risk of atherosclerosis and coronary disease in visceral obesity. Fish oils lower plasma triacylglycerols, but the underlying mechanisms are not fully understood. OBJECTIVE We studied the effect of fish oils on the metabolism of apolipoprotein B-100 (apo B) and chylomicron remnants in obese men. DESIGN Twenty-four dyslipidemic, viscerally obese men were randomly assigned to receive either fish oil capsules (4 g/d, consisting of 45% eicosapentaenoic acid and 39% docosahexaenoic acid as ethyl esters) or matching placebo (corn oil, 4 g/d) for 6 wk. VLDL, intermediate-density lipoprotein (IDL), and LDL apo B kinetics were assessed by following apo B isotopic enrichment with the use of gas chromatography-mass spectrometry after an intravenous bolus injection of trideuterated leucine. Chylomicron remnant catabolism was measured with the use of an intravenous injection of a chylomicron remnant-like emulsion containing cholesteryl [(13)C]oleate, and isotopic enrichment of (13)CO(2) in breath was measured with isotope ratio mass spectrometry. Kinetic values were derived with multicompartmental models. RESULTS Fish oil supplementation significantly (P < 0.05) lowered plasma concentrations of triacylglycerols (-18%) and VLDL apo B (-20%) and the hepatic secretion of VLDL apo B (-29%) compared with placebo. The percentage of conversions of VLDL apo B to IDL apo B, VLDL apo B to LDL apo B, and IDL apo B to LDL apo B also increased significantly (P < 0.05): 71%, 93%, and 11%, respectively. Fish oils did not significantly alter the fractional catabolic rates of apo B in VLDL, IDL, or LDL or alter the catabolism of the chylomicron remnant-like emulsion. CONCLUSION Fish oils effectively lower the plasma concentration of triacylglycerols, chiefly by decreasing VLDL apo B production but not by altering the catabolism of apo B-containing lipoprotein or chylomicron remnants.