Objective: The objective of this clinical trial was to examine the efficacy of a supplement containing natural S-(-)equol, a daidzein metabolite, in reducing menopausal symptoms.
Methods: In this multicenter, double-blind placebo-controlled trial, 160 equol nonproducing, postmenopausal Japanese women who experienced at least 1 hot flush/day were randomly assigned to consume 10 mg/day S-(-)equol (n=77 women) or placebo (n=83 women) for 12 weeks. Participants completed a standardized menopausal symptom checklist and rated five common menopause symptoms by a visual analog scale at baseline, week 12, and week 18 (6-week postintervention). Physical, blood, and urine examinations were conducted. One hundred twenty-six women completed the study.
Results: At baseline, daily hot flush frequency was 2.9±2.1 for the S-(-)equol group and 3.2±2.4 for the placebo group. After the 12-week intervention, the S-(-)equol group had a greater decrease from baseline in hot flush frequency compared with the placebo group (-1.9±1.8/day, -58.7%, vs. -1.0±2.0/day, -34.5%, p=0.009). The severity of hot flushes and neck or shoulder muscle stiffness significantly decreased in the S-(-)equol group compared with the placebo group. No changes in clinical parameters or serious adverse effects were reported.
Conclusions: This is the first trial to show beneficial effects of a 10-mg natural S-(-)equol supplement consumed daily for 12 weeks on major menopausal symptoms, specifically, hot flushes and neck or shoulder muscle stiffness, in postmenopausal Japanese women. This supplement offers a promising alternative for management of menopausal symptoms.