• Progression of subclinical atherosclerosis measured by the rate of change in distal common carotid artery far wall intima-media thickness in computer image processed B-mode ultrasonograms [ Time Frame: Baseline and every 6 months ] [ Designated as safety issue: No ]
  

• Longitudinal change in cognitive function, bone mineral density, and mammographic percent density [ Time Frame: Cognitive function: Baseline and end-of-study; Bone mineral density: Baseline, 12 month, 30 month; Mammographic percent density: Baseline, 12 month, 24 month ] [ Designated as safety issue: No ]
  

Heart disease is the leading cause of death among women in the United States. Atherosclerosis, a primary cause of heart disease, accounts for more than 485,000 heart attacks and 370,000 strokes each year in American women. Data indicate that a woman's risk of suffering from an atherosclerosis-related cardiovascular event significantly increases after menopause; this risk may be due to reduced estrogen production associated with menopause. Soy isoflavones are plant compounds that are structurally similar to human estrogen. Evidence suggests that soy supplements may provide the same protection against heart disease as estrogen in postmenopausal women. This study will determine the effects of soy supplements on atherosclerosis progression, cognition, bone mineral density, and breast tissue density changes in postmenopausal women.

This study will last 2.5 years. Participants will be randomly assigned to receive either soy supplements or placebo daily for the duration of the study. The active product, which will be given as two divided doses, is 25 g soy protein containing 85 mg aglycone weight naturally-occurring isoflavones (150 mg total isoflavone), genistein 45 mg aglycone weight (80 mg total weight), daidzein 35 mg aglycone weight (60 mg total weight) and glycitein 5 mg aglycone weight (10 mg total weight). Blood collection, cognitive tests, and mammograms will be used to assess participants at study entry, at each monthly visit, and at study completion.