OBJECTIVETo examine the change in menopausal symptoms and cardiovascular risk factors in response to 4 months of daily 100-mg soy isoflavone in postmenopausal women.METHODSIn this double-blind, placebo-controlled study, 80 women were randomly assigned to isoflavone (n= 40) and placebo (n= 40) treatment. The menopausal Kupperman index was used to assess change in menopausal symptoms at baseline and after 4 months of treatment. Cardiovascular risk factors were assessed by evaluating plasma lipid levels, body mass index, blood pressure, and glucose levels in the participants. To examine the effects of this regime on endogenous hormone levels, follicle-stimulating hormone (FSH), luteinizing hormone (LH), and 17β-estradiol were measured. Transvaginal sonography was performed to quantify endometrial thickness.RESULTSThe data showed a decrease in menopausal symptoms (P< .01, pairedttest, two-tailed, between baseline and isoflavone groups, andP< .01, unpairedttest, between placebo and isoflavone groups). Total cholesterol and low-density lipoprotein decreased significantly in the isoflavone group compared with the baseline or placebo group (P< .001, pairedttest, two-tailed, between baseline and isoflavone groups, andP< .01, unpairedttest, between placebo and isoflavone groups). The isoflavone treatment appeared to have no effect on blood pressure, plasma glucose, and high-density lipoprotein and triglyceride levels.CONCLUSIONThis study suggests that isoflavone 100-mg regime treatment may be a safe and effective alternative therapy for menopausal symptoms and may offer a benefit to the cardiovascular system.