A monounsaturated fatty acid-rich diet reduces macrophage uptake of plasma oxidised low-density lipoprotein in healthy young men

During atherogenesis, a pathological accumulation of lipids occurs within aortic intimal macrophages through uptake of plasma oxidised LDL (oxLDL). The aim of the present study was to determine whether macrophage uptake of plasma oxLDL and LDL susceptibility to oxidation may be determined by quantity and quality of dietary fat. Twenty healthy young men were subjected to three dietary periods, each lasting 4 weeks. The first was an SFA-enriched diet (38% fat, 20% SFA), which was followed by a carbohydrate (CHO)-rich diet (30% fat, < 10% SFA, 55 % CHO) or a MUFA olive oil-rich diet (38 % fat, 22 % MUFA) following a randomised cross-over design. After each diet period, LDL particles were oxidised with Cu ions to determine LDL susceptibility to oxidation and subsequently incubated with the U937-macrophage cell line to determine the percentage of uptake of plasma oxLDL. The shift from the MUFA diet to the SFA- or CHO-rich diets reduced the resistance of LDL particles to oxidation, decreasing lag time (P=0.038) and increasing the propagation rate (P=0.001). Furthermore, the MUFA-rich diet demonstrated reduced macrophage uptake of plasma oxLDL (P= 0.031) as compared with the SFA-rich diet. Finally, macrophage uptake of plasma oxLDL was correlated (r 0.45; P=0.040) with total amount of conjugated dienes after LDL oxidation. Our data suggest that a MUFA-rich diet may have favourable effects on cardiovascular risk since it prevents the oxidative modifications of LDL and reduces macrophage uptake of plasma oxLDL.