Antioxidant effect of isoflavones: A randomized, double-blind, placebo controlled study in oophorectomized women

Background: One of the postulated mechanism for cardioprotective potential of isoflavones is their ability to exert antioxidant action. However, various reports give conflicting results in this area. Aim: The present study was conducted with an objective to probe into the cardioprotective mechanism of isoflavones by evaluating their antioxidant potential in oophorectomized women. Materials and Methods: This was a randomized, double-blind, parallel, placebo controlled study. A total of 43 women were randomized to receive 75 mg/day isoflavones tablet or placebo for 12 weeks. Red blood cell antioxidant parameters including lipid peroxidation, superoxide dismutase (SOD), catalase and glutathione peroxidase (GSH-Px) were determined at baseline and at the end of the study. Results: After 12 weeks of administration of isoflavones, there was no statistically significant difference in lipid peroxidation ( P value for isoflavones: 0.37; for placebo: 0.37), catalase ( P value for isoflavones: 0.35; for placebo: 0.84), SOD ( P value for isoflavones: 0.41; for placebo: 0.28) and GSH-Px ( P value for isoflavones: 0.92; for placebo: 0.29). There was no statistically significant difference in the proportion of patients experiencing adverse events in the two groups ( P -1.00). Conclusion: The study strengthens the concept that the cardioprotective mechanism of isoflavones might be due to some other reason apart from the antioxidant pathway.