Effects of high-dose phytoestrogens on circulating cellular microparticles and coagulation function in postmenopausal women

Background/Purpose: Estrogen in hormone replacement therapy causes homeostatic changes. However, little is known regarding the safety of high-dose phytoestrogen on coagulation and hematological parameters in healthy postmenopausal women. This study evaluated the effects of high-dose soy isoflavone (300 mg/day) on blood pressure, hematological parameters, and coagulation functions including circulating microparticles in healthy postmenopausal women. Methods: The original study is a 2-year prospective, double-blind, placebo-controlled study. In total, 431 postmenopausal women (from 3 medical centers) were randomly assigned to receive either high-dose isoflavone or placebo for 2 years. At baseline, 6 months, 1 year, and 2 years after treatment, blood pressure, body weight, liver function tests, hematological parameters, and lipid profiles were measured. The 1^st year blood specimens of 85 cases of 144 eligible participants (from one of the three centers) were analyzed as D-dimer, von Willebrand factor antigen, factor VII, plasminogen activator inhibitor type 1, and circulating cellular microparticles, including the measurement of monocyte, platelet, and endothelial microparticles. Results: In the isoflavone group, after 1 year, the changes in liver function tests, hematological parameters, and coagulation tests were not different from those of the control. Triglyceride levels were significantly lower after 6 months of isoflavone treatment than the placebo group, but the difference did not persist after 1 year. Endothelial microparticles increased steadily in both groups during the 1-year period but the trend was not affected by treatment. Conclusion: The results of the present study indicate that high-dose isoflavone treatment (300 mg/day) does not cause hematological abnormalities or activate coagulation factors.