Oleic acid rich diet protects against the oxidative modification of high density lipoprotein

Oxidative modifications of lipoproteins could contribute to the development of atherosclerosis, but the influence of dietary fats on high density lipoprotein (HDL) oxidative modification is unknown. This study was designed to determine whether a diet rich in oleic acid could modulate the oxidative modification of HDL3. Twenty two healthy men were randomly placed on a 32-wk crossover study of an oleic acid rich diet supplied by a variant of sunflower oil vs a linoleic acid rich diet provided by conventional sunflower oil. Plasma HDL3 obtained after the diet rich in oleic acid showed a significantly higher oleic acid content in the phospholipid than lipoprotein isolated after the linoleic acid rich diet. HDL3 isolated after the oleic acid rich diet had lower values of thiobarbituric acid reactive substances (TBARS) than HDL3 obtained after the linoleic acid rich diet both for native (mean +/- SE; 0.24 +/- 0.02 vs 0.42 +/- 0.08 nmol MDA/mg protein; p < 0.01) and copper oxidized HDL3 (0.75 +/- 0.06 vs 0.95 +/- 0.07 nmol MDA/mg protein; p < 0.01). Indeed, TBARS for native HDL3 were negatively correlated with the oleic acid to linoleic acid ratio and positively with the percentage of linoleic acid in their phospholipids. Interestingly, HDL3 after both diets had similar antioxidant vitamins A and E content. HDL3 overall composition and fluidity were similar after the two diets. Moreover, HDL3 obtained after both diets produced identical [3H] free cholesterol efflux from human monocyte-derived macrophages (29%) and fibroblasts (26%). In conclusion, HDL3 rich in oleic acid was less easily oxidized regardless of the content of antioxidants such as vitamins A and E. Therefore, dietary monounsaturated fatty acid prevent the oxidative modification of lipoproteins.