Effects of fish oil fatty acids on plasma lipids and lipoproteins and oxidant-antioxidant imbalance in healthy subjects

The purpose of this study was to investigate the effect of eicosapentaenoic and docosahexaenoic acids on plasma lipids and lipoproteins, lipid peroxid ation and antioxidant status in healthy humans. A total of 19 healthy volun teers consumed 6 g/day Maxepa(R) fish oil for 3 weeks (1.8 g n-3 fatty acid s/day). At baseline and at day 21, we evaluated plasma lipoproteins, plasma and low-density lipoprotein fatty acids, lipid peroxidation markers (malon dialdehyde concentration, low-density lipoprotein peroxidation in vitro), a nd the content of a number of antioxidants (reduced and oxidized glutathion e in whole blood, plasma and erythrocyte glutathione peroxidases, plasma vi tamin E and beta carotene). Plasma concentrations of total cholesterol, tri glycerides, phospholipids, low-density lipoprotein cholesterol and low-dens ity lipoprotein size did not differ significantly after 3 weeks of suppleme ntation. Adding the fish oil to the diet increased the concentration of n-3 very-long-chain polyunsaturated fatty acids and decreased the concentratio n of n-6 fatty acid and oleic acid in plasma and low-density lipoprotein. E icosapentaenoic and docosahexaenoic acid supplementation caused elevated va lues of the high-density lipoprotein cholesterol due to an increment of the high-density lipoprotein 2 fraction and reduced low-density lipoprotein pe roxidation rate in vitro. However, we observed an imbalance between oxidiza ble substrates and antioxidants with an increased lipid peroxidation, where as the content of reduced glutathione and beta carotene decreased without a ny variation in vitamin E. Association of antioxidants with n-3 PUFA could prevent lipid peroxidation and enhance the antiatherogenic effects of n-3 p olyunsaturated fatty acids.