Consuming 10 milligrams daily of S-equol delivered via a new fermented soy-based nutritional supplement alleviated menopausal symptoms, particularly the frequency of hot flashes and severity of neck or shoulder muscle stiffness, without impacting thyroid and certain sex hormone levels, according to clinical data presented at the annual meeting of The Endocrine Society, (ENDO) 2013.
"This study provides evidence that the daily 10 mg doses of S-equol, a metabolite of the soy isoflavone daidzein, reduced hot flash frequency and relieved muscle stiffness without affecting sex or thyroid hormone levels of Japanese postmenopausal women. The findings confirm and expand on other studies in Japanese and U.S. women documenting the ability of S-equol to help relieve menopausal symptoms," said Belinda H. Jenks, Ph.D., coauthor of the study and director of Scientific Affairs & Nutrition Education at Pharmavite LLC. Development and ongoing research of a supplement containing S-equol is conducted by the Saga Nutraceuticals Research Institute of Otsuka Pharmaceutical Co., Ltd. Pharmavite LLC, the makers of Nature Made® vitamins and minerals, is a subsidiary of Otsuka, which supported the study.
The data presented at ENDO 2013 include results of a dose-finding study and larger confirmation study, both of which were randomized, double-blind and placebo-control trials examining 12 weeks of treatment using a supplement containing S-equol in Japanese postmenopausal women who could not produce S-equol themselves.
S-equol [7-hydroxy-3-(4'-hydroxyphenyl)-chroman] is a compound resulting from the natural metabolism, or conversion, of daidzein, an isoflavone found in whole soybeans. Not everyone can produce S-equol after soy consumption, as the production depends on the types of bacteria present in the large intestine and may be influenced by the amount of soy consumed. About 50 percent of Asians and 20 to 30 percent of North Americans and Europeans, who in general consume less soy than Asians, produce S-equol. Preliminary evidence from observational studies is emerging that suggests that women who are S-equol producers may experience fewer menopausal symptoms compared to non-producers.
Hormones Remain Steady, While Menopausal Symptoms Improve in Confirmation Study
Measurement of the sex hormones estradiol (estrogen), follicle stimulating hormone (FSH) and testosterone as well as of the thyroid hormones thyroid stimulating hormone (TSH), Free T4 (thyroxine) and Free T3 (triiodothyronine) documented no significant difference after 12 weeks of treatment in 77 women receiving 10 mg/daily of S-equol compared to 83 women receiving a placebo (p values ranged from 0.2092 to 0.3942).
Researchers assessed the effects of S-equol using the Climacteric Symptom Evaluation Form Checklist, which contains 22 menopausal symptoms. The women reported significant decreases in the severity of hot flashes as well as of muscle stiffness of the neck and shoulder after 12 weeks of treatment with S-equol compared to a placebo (p=0.015 for both). Frequency of hot flash measures were also significantly reduced after 12 weeks of treatment, with hot flashes declining on average by 58.7 percent (-1.9 ± 1.8 episodes daily) with S-equol compared to 34.5 percent (-1.0 ± 2.0 episodes daily) with a placebo (p=0.009).
A separate measure using the Visual Analog Scale for menopausal symptoms documented a significant change in muscle stiffness of neck and shoulder after the 12-week treatment period for those receiving S-equol compared to a placebo (p=0.007).
The confirmation study evaluated 160 women aged 45 to 60 years, who had scored 25 or more on the Simplified Menopausal Index (SMI), a rating scale for menopausal symptoms. Women who had a greater than 50 percent response on the SMI scale while using a placebo during a four-week screening period prior to the treatment phase were excluded from the study. The use of the 10 mg daily dose of S-equol was based on the data from the prior pilot dose-finding study, which determined that 10 mg of S-equol was the active dose needed to alleviate menopausal symptoms.