Effects of Equol Supplement on Bone and Cardiovascular Parameters in Middle-Aged Japanese Women: A Prospective Observational Study

Objective: To examine changes in the bone and cardiovascular parameters and tolerability in middle-aged Japanese women taking equol supplement for a year. Design: This was a prospective observational study. Subjects and Setting: Participants were 74 women receiving outpatient care at Hamasite Medical Clinic, Minato-ku, Tokyo, from 2013 to 2015. Interventions: Participants received per oral equol-containing supplement, 10 mg/day. Outcome measures: The primary outcome measures were percent changes in bone and cardiovascular parameters after 1 year supplementation with equol. The secondary measures included factors affecting the parameter changes and adverse effects associated with equol use for a year. Results: Reduction in arterial stiffness was observed after 12 months of equol supplement (1402.3 cm/s vs.1367.3 cm/s, p < 0.001). Significant reductions in respective parameters were observed in women with moderate and high risk for arteriosclerosis (median [95% confidence interval]: −3.2% [−5.79 to −0.74]; −12.65% [−18.52 to −4.28]; respectively); hypertriglyceridemia −45.53% [−70.24 to −5.58]; bone resorption risk (−15.15% [−23.71 to 1.56]; and bone fracture risk −26.68% [−76.43 to −5.99]. All 15 women with high baseline parathyroid hormone levels had achieved a median of 50% [−54.11 to −31.69] reduction from their baseline values. These associations were further confirmed in the results of multiple linear regression analysis. There were no reported adverse events or abnormal findings in the blood chemistry, Pap smear, mammography, and transvaginal ultrasound during periodic follow-ups. Conclusion: One year equol supplement was tolerable and induced improvement of certain bone and cardiovascular parameters, especially in higher risk groups. Further controlled studies are needed to explore long-term equol use for wellbeing of middle-aged women.