PURPOSEIncreased intake of omega‐3 polyunsaturated fatty acids (n−3 PUFA) appear to have antioxidant properties. The purpose of this study was to examine the chronic effect of n−3 PUFA supplementation and aerobic training on oxidative stress markers in obese women.METHODSWe performed a randomized, placebo‐controlled, double‐blind design on 43 obese women (48.5±2y; 39.7±5% body fat, 33.8±3 kg/m2, Supplement [SUP] n=11, Aerobic Training [AT] n=12, Supplement‐Aerobic Training [SAT] n=11, and Placebo [PLA] n=9). Oxidative stress markers including total antioxidant capacity (TAC), catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) were measured at baseline and at week 8. All participants were asked to maintain their normal dietary intake throughout study. Participants in AT and SAT groups were required to follow an aerobic training program which was 45‐min running on the treadmill with 45–65% HRmax (3 d/wk) for an 8‐wk period, while the SUP and PLA groups did not perform any training program. Participants received either 4 g of fish oil (56% docosahexaenoic acid (DHA) and 28% eicosapentaenoic acid (EPA) or placebo (olive oil) in four divided doses per day for an 8‐week period. Data were analyzed by GLM and presented as mean (SD).RESULTSWe observed a significant increase in serum TAC in SUP and SAT groups, but not in AT and PLA groups (p<0.04). The level of CAT was significantly higher only in SAT, but not in any other groups (p<0.01). We did not observe any significant change in serum SOD and GPx levels among the groups (p>0.05).CONCLUSIONThe present findings suggest that 4 g/day of fish oil for an 8‐week period, increase the activity of TAC and antioxidant enzymes. Fish oil supplementation might be considered as a protective strategy to improve the status of antioxidant defense system in obese women.Support or Funding InformationThis study was not funded.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.