Background: Previous data have suggested that genistein, a soy-derived isoflavone, could exert beneficial effects on cardiovascular function and metabolic homeostasis in postmenopausal women.

Aim and Methods: We aimed to evaluate the effects of genistein in postmenopausal women with metabolic syndrome. We enrolled 120 postmenopausal women with metabolic syndrome according to modified NCEP-ATP III criteria. All participants gave written informed consent in accordance with the Declaration of Helsinki. Postmenopausal women with metabolic syndrome were randomly assigned to receive placebo (n=60) or 54 mg/day of genistein (n=60) for 1 year. The primary outcome was homeostasis model assessment for insulin resistance (HOMA-IR) at 1 year. Secondary outcomes were fasting glucose, fasting insulin, total cholesterol, Low-Density Lipoprotein Cholesterol (LDL-C), High Density Lipoprotein-Cholesterol (HDL-C), triglycerides, visfatin, adiponectin and homocysteine blood levels. Data on adverse events were also recorded.

Results: At 1 year, fasting glucose, fasting insulin and HOMA-IR had decreased in genistein recipients and unchanged in placebo recipients. Genistein statistically increased HDL-C and adiponectin and decreased total cholesterol, LDL-C, visfatin and homocysteine serum levels. No placebo or genistein patients discontinued treatment because of adverse events.

Conclusions: One year of treatment with genistein, in the context of appropriate physical activity and an adequate dietary regimen, effectively manages the metabolic syndrome in postmenopausal women.