Effects of high-dose isoflavones on metabolic and inflammatory markers in healthy postmenopausal women.

Context—After menopause, women experience changes in body composition, especially increase in fat mass. Additionally, advancing age, decreased physical activity and increased inflammation may predispose them to develop type-2 diabetes. Isoflavones have been shown to improve metabolic parameters in postmenopausal women. However, the effect of isoflavones on adipo-cytokines remains unclear. Objective—To evaluate the effect of high dose isoflavones on inflammatory and metabolic markers in postmenopausal women. Study Design—We measured glucose, insulin and adipokines/cytokines in 75 healthy postmenopausal women who were randomized to receive 20 gm of soy protein with 160 mg of total isoflavones (64mg genistein, 63 mg diadzein, 34 mg glycitein) or 20 gm of soy protein placebo for 12 weeks. Women on estrogen discontinued therapy at least three months prior to the study. The supplements were given in a powder form and consumed once daily with milk or other beverages. Results—Mean age in the placebo and active groups was similar (p=0.4). Average time since menopause was 9 yrs and two-thirds of the women underwent natural menopause. There was no significant difference in the BMI at baseline between the groups [placebo (25.1 kg/m2), active (26 kg/m2)] and it did not change significantly during the study. At baseline, placebo group had significantly higher levels of TNF-α (p<0.0001), otherwise there was no difference in any other parameter. After 12 weeks of treatment, there were significant positive changes in TNF-α levels within the placebo group (p<0.0001) and adiponectin levels within the isoflavones group (p=0.03). Comparison of pre-post change between the groups showed a small but significant increase in serum adiponectin levels in the isoflavone group (p=0.03) compared to placebo. No significant changes were seen in any other parameter between the two groups. Conclusion—Healthy, normal-weight postmenopausal women may not experience improvement in metabolic parameters when given high dose isoflavones despite an increase in serum adiponectin levels. Role of isoflavones in obese and insulin resistant postmenopausal women needs exploration.