Context: Limited data are available evaluating the effects of soy isoflavones on metabolic status of patients with polycystic ovary syndrome (PCOS).
Objective: The current study was performed to determine the effects of soy isoflavones on metabolic status of patients with PCOS.
Methods: This randomized, double-blind, placebo-controlled trial was performed on 70 women diagnosed with PCOS according to the Rotterdam criteria who were 18-40 years old. Participants were randomly allocated into two groups to take either 50 mg/d soy isoflavones (n = 35) or placebo (n = 35) for 12 weeks. Metabolic, endocrine, inflammation, and oxidative stress biomarkers were quantified at the beginning of the study and after the 12-week intervention.
Results: After 12 weeks of intervention, compared to the placebo group, soy isoflavone administration significantly decreased circulating serum levels of insulin (-1.2 ± 4.0 vs +2.8 ± 4.7 μIU/mL; P < .001) and homeostasis model of assessment-estimated insulin resistance (-0.3 ± 1.0 vs +0.6 ± 1.1; P < .001) and increased the quantitative insulin sensitivity check index (+0.0009 ± 0.01 vs -0.01 ± 0.03; P = .01). Supplementation with soy isoflavones resulted in significant reductions in free androgen index (-0.03 ± 0.04 vs +0.02 ± 0.03; P < .001) and serum triglycerides (-13.3 ± 62.2 vs +10.3 ± 24.5 mg/dL; P = .04) compared to the placebo group. There was a significant increase in plasma total glutathione (+96.0 ± 102.2 vs +22.7 ± 157.8 μmol/L; P = .04) and a significant decrease in malondialdehyde levels (-0.7 ± 0.8 vs +0.8 ± 2.3 μmol/L; P = .001) by soy isoflavone intake compared with the placebo group. We did not observe any significant effect of soy isoflavone intake on other lipid profiles and inflammatory and oxidative stress markers.
Conclusion: Soy isoflavone administration for 12 weeks in women with PCOS significantly improved markers of insulin resistance, hormonal status, triglycerides, and biomarkers of oxidative stress.