The effects of natural S-equol supplementation on skin aging in postmenopausal women: a pilot randomized placebo-controlled trial

Objective: The aim of this study was to investigate the effects of the natural S-equol supplement on skin aging in equol-nonproducing Japanese postmenopausal women. Methods: A randomized, double-blind, placebo-controlled trial examined the use of the natural S-equol supplement for 12 weeks in 101 postmenopausal Japanese women who were equol nonproducers. They were randomly assigned to one of three groups: placebo (n = 34), 10 mg S-equol/day (EQL10; n = 34), or 30 mg S-equol/day (EQL30; n = 33). Skin parameters of crow's-feet wrinkles (area and depth), hydration, transepidermal water loss, and elasticity were measured at baseline and at monthly intervals during treatment. Vaginal cytology, endometrial thickness, and mammography were performed before and after treatment. Serum hormone concentrations were measured at the same time as skin parameters. Results: The EQL10 and EQL30 groups showed significant reductions in wrinkle area compared with the placebo group (P < 0.05). There was a significant difference in wrinkle depth between the placebo group and the EQL30 group (P < 0.05). Other skin parameters did not show significant differences after the treatment in any group. There were no abnormal results in hormone status or gynecological examinations. Conclusions: Our data suggest that natural S-equol supplementation (EQL10 and EQL30) may have a beneficial effect on crow's-feet wrinkles in postmenopausal women without serious adverse events.