Supplementation of postmenopausal women with fish oil rich in eicosapentaenoic acid and docosahexaenoic acid is not associated with greater in vivo lipid peroxidation compared with oils rich in oleate and linoleate as assessed by plasma malondialdehyde and F-2-isoprostanes

Background: Although the replacement of dietary saturated fat with unsatura ted fat has been advocated to reduce the risk of cardiovascular disease, di ets high in polyunsaturated fatty acids (PUFAs) could increase lipid peroxi dation, potentially contributing to the pathology of atherosclerosis. Objective: The objective of this study was to examine indexes of in vivo li pid peroxidation, including free F-2-isoprostanes, malondialdehyde (MDA), a nd thiobarbituric acid reacting substances (TBARS), in the plasma of postme nopausal women taking dietary oil supplements rich in oleate, linoleate, an d both eicosapentaenoic acid and docosahexaenoic acid. Design: Fifteen postmenopausal women took 15 g sunflower oil/d, providing 1 2.3 g oleate/d; safflower oil, providing 10.5 g linoleate/d; and fish oil, providing 2.0 g EPA/d and 1.4 g DHA/d in a 3-treatment crossover trial. Results: Plasma free F-2-isoprostane concentrations were lower after fish-o il supplementation than after sunflower-oil supplementation (P = 0.003). Wh en plasma free F-2-isoprostane concentrations were normalized to plasma ara chidonic acid concentrations, significant differences among the supplements were eliminated. Plasma MDA concentrations were lower after fish-oil suppl ementation than after sunflower-oil supplementation (P = 0.04), whereas pla sma TBARS were higher after fish-oil supplementation than after sunflower o il (P = 0.003) and safflower oil (P = 0.001) supplementation. When plasma M DA concentrations were normalized to plasma PUFA concentrations, significan t differences were eliminated, but TBARS remained higher after fish-oil sup plementation than after sunflower oil (P = 0.01) and safflower-oil (P = 0.0 003) supplementation. Conclusions: With fish-oil supplementation, then was no evidence of increas ed lipid peroxidation when assessed by plasma F-2-isoprostanes and MDA, alt hough plasma TBARS was higher than with sunflower-oil and safflower-oil sup plementation.