S-equol Reduces Menopausal Symptoms Without Impacting Thyroid, Sex Hormones

NORTHRIDGE, Calif.A daily 10-mg dose of S-equol reduced menopausal symptoms without impacting thyroid and sex hormones, according to new research published in The Journal of Nutrition (2010 Jul;140(7):1386S-9S. DOI: 10.3945/jn.109.118307).

Findings indicated consuming 10 mg 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.

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 because production depends on the types of bacteria present in the large intestine, which 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 generally consume less soy than Asians, produce S-equol. Preliminary evidence from observational studies is emerging that suggests women who are S-equol producers may experience fewer menopausal symptoms compared to non-producers.

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, a subsidiary of Otsuka, which supported the study.

The new data, which was presented at an annual meeting of The Endocrine Society, included results of a dose-finding study and larger confirmation study, both of which were randomized, double blind and placebo-controlled trials. During a 12-week period, researchers issued treatments using a supplement containing S-equol to Japanese postmenopausal women who could not produce S-equol themselves.

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 of S-equol compared to 83 women receiving a placebo.

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. Frequency of hot flash measures were also significantly reduced, with hot flashes declining on average by 58.7 percent with S-equol compared to 34.5 percent with a placebo.

A separate measure using the Visual Analog Scale for menopausal symptoms documented a significant change in muscle stiffness of neck and shoulder for those receiving S-equol compared to a placebo.

The confirmation study evaluated 160 women ages 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.

Past research also shows a whole soy supplement containing S-equol reduces muscle and joint pain, along with menopausal symptoms.