Peroxidation of LDL From Combined-Hyperlipidemic Male Smokers Supplied With ¯-3 Fatty Acids and Antioxidants

Abstract

The effects of marine ¯-3 polyunsaturated fatty acids (FAs) and antioxidants on the oxidative modification of LDL were studied in a randomized, double-blind, placebo-controlled trial. Male smokers (n=41) with combined hyperlipidemia were allocated to one of four groups receiving supplementation with ¯-3 FAs (5 g eicosapentaenoic acid and docosahexaenoic acid per day), antioxidants (75 mg vitamin E, 150 mg vitamin C, 15 mg β-carotene, and 30 mg coenzyme Q₁₀ per day), both ¯-3 FAs and antioxidants, or control oils. LDL and human mononuclear cells were isolated from the patients at baseline and after 6 weeks of supplementation. LDL was subjected to cell-mediated oxidation by the patients’ own mononuclear cells, as well as to Cu²⁺-catalyzed and 2,2′-azobis-(2-amidinopropane hydrochloride) (AAPH)–initiated oxidation. Extent of LDL modification was measured as lag time, the formation rate of conjugated dienes (CDs), the maximum amount of CDs formed, formation of lipid peroxides, and the relative electrophoretic mobility of LDL on agarose gels. Dietary supplementation with ¯-3 FAs increased the concentration of total ¯-3 FAs in LDL and reduced the concentration of vitamin E in serum. The ¯-3 FA–enriched LDL particles were not more susceptible to Cu²⁺-catalyzed, AAPH-initiated, or autologous cell–mediated oxidation than control LDL. In fact, enrichment with ¯-3 FAs significantly reduced the formation rate of CDs when LDL was subjected to AAPH-induced oxidation. Supplementation with moderate amounts of antioxidants significantly increased the concentration of vitamin E in serum and increased the resistance of LDL to undergo Cu²⁺-catalyzed oxidation, measured as increased lag time, reduced formation of lipid peroxides, and reduced relative electrophoretic mobility compared with control LDL. Supplementation with ¯-3 FAs/antioxidants showed oxidizability of LDL similar to that of control LDL and ¯-3 FA–enriched LDL. In conclusion, ¯-3 FAs neither rendered the LDL particles more susceptible to undergo in vitro oxidation nor influenced mononuclear cells’ ability to oxidize autologous LDL, whereas moderate amounts of antioxidants protected LDL against oxidative modification.