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

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.

The present study was conducted with an objective to probe into the cardioprotective mechanism of isoflavones by evaluating their antioxidant potential in oophorectomized women.

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.

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).

The study strengthens the concept that the cardioprotective mechanism of isoflavones might be due to some other reason apart from the antioxidant pathway.