A new peer-reviewed pilot study reported in a poster at the North American Menopause Society (NAMS) annual scientific meeting has revealed that post-menopausal women experienced improvements in vaginal atrophy, with no significant effect on hormone levels or genital bleeding, after 12 weeks of daily 10 milligram (mg) doses of an investigational fermented soy germ-based nutritional supplement.
"These data documented improved vaginal epithelium, without significant abnormalities in vaginal cells, endometrial thickening, hormone levels or genital bleeding, which adds to the known safety profile of this S-equol supplement," said coauthor Belinda H. Jenks, Ph.D., director of Scientific Affairs & Nutrition Education at Pharmavite LLC, the makers of Nature Made® vitamins and minerals and a subsidiary of Otsuka Pharmaceutical Co., Ltd., which supported the study.
In menopausal women, estrogen loss is the major cause of atrophy of the tissues of the reproductive and urinary systems, which usually is progressive (Calleja-Agius and Brincat, 2009) and includes vaginal dryness, itching, burning, dyspareunia (painful intercourse) and urinary incontinence. While estrogen replacement therapy can help manage these symptoms, some women do not use such hormone-based therapy because of side effect concerns (Uchiyama et al., 2014).
S-equol has the ability to bind to the same estrogen receptors as naturally occurring estrogen, with a stronger affinity to the beta receptor compared to the alpha receptor. On binding to the receptor, S-equol mimics some, but not all, activities of estrogen. Because of these actions at the receptor, it has been proposed that S-equol may alleviate some symptoms caused by diminished estrogen production during menopause. Daily doses of the supplement containing S-equol, a metabolite of the soy isoflavone daidzein, can relieve hot flash frequency and muscle and joint pain, as reported in previously published controlled clinical trials in both U.S. and Japanese postmenopausal women.
Vaginal and Reproductive Health Benefits
Daily 10 mg doses of S-equol for 12 weeks showed an improvement in vaginal epithelium in 105 post-menopausal Japanese women, who were not S-equol producers. The researchers used the percentage of superficial cells, to determine vaginal atrophy, as the disappearance of these cells is associated with dryness and increased risk of some conditions such as candida (yeast) infections, known to cause itch and inflammation.
Investigators examined three daily doses of S-equol, 2, 6 and 10 mg, and a placebo, with tissue evaluations at the study start and 12 weeks. Specifically, the 10 mg group showed a positive trend to superiority compared to the placebo group, respectively +6.3 vs. -4.4 percent change in superficial cells at 12 weeks, P=0.0507, while the 2 and 6 mg groups showed dose-related changes of -2.2 and +2.7 percent, (P=0.6350 and P=0.2011) respectively, which did not differ significantly from the placebo group. None of the groups displayed an increase in abnormal vaginal cells.
Likewise, the women's change in endometrial thickness after 12 weeks showed no significant differences between groups: 3.6±1.1 millimeter (mm) in the placebo group, 4.0±1.1 mm for the 2 mg group, 3.8±2.3 for the 6 mg group, and 4.6±2.4 mm for the 10 mg group. No treatment group showed significant genital bleeding. Additionally, no significant differences occurred in the groups based on measures of their blood levels of estrogen, follicle stimulating hormone, testosterone, thyroid-stimulating hormone, triiodothyronine (T3) and thyroxine (T4).
Complete data from the study will be submitted to a peer-review journal for publication.