Eating more soy was associated with larger reductions in menopausal vasomotor symptoms (VMS), such as hot flashes, among U.S. women that can convert soy to a compound called equol, according to data from a first-of-its-kind study presented in an oral session at the North American Menopause Society (NAMS) 2012 annual meeting.

“Numerous studies have examined the association between soy isoflavones – from both soy foods and supplements - and menopausal VMS, but with mixed results,” said Belinda H. Jenks, Ph.D., Director of Scientific Affairs & Nutrition Education at Pharmavite LLC., which funded the prospective observational study. “However, they do not routinely account for whether the enrolled women can produce equol, which has documented reductions on certain VMS such as hot flashes.”

The study, conducted by researchers at the Group Health Research Institute, University of Washington and the Fred Hutchinson Cancer Institute, is the first to examine equol production status and the effect of varied soy consumption on VMS in menopausal U.S. women. Evidence from prior observational studies suggests that Japanese women have milder menopausal symptoms in those who are equol producers compared to nonproducers. Additional peer-reviewed studies have documented that dietary supplements containing equol have reduced VMS symptoms in postmenopausal women who are not equol producers.

Equol is produced from the natural metabolism, or conversion, of daidzein, an isoflavone found in whole soybeans. Not everyone can produce equol after soy consumption, as the production depends on the types of bacteria present in the large intestine. About 50 percent of Asians and 20 to 30 percent of North Americans and Europeans, who in general consume less soy than Asians, have the ability to produce equol.

NAMS Study Quantifies VMS Reduction in US Equol Producers

Consuming higher levels of soy containing daidzein was associated with fewer VMS, but only among the women who were equol producers.

Among the 129 equol producers, 36 percent of the study’s 355 participants, those consuming the most daidzein in their daily diet, versus those with the least daidzein, were 76 percent more likely to have fewer than the study’s daily average number of VMS, 2.33. The positive trend in the equol producers between increased daidzein consumption and reduced VMS symptoms occurred across all four intake levels of daidzein (p=0.06). In comparison, no associations between daidzein intake and VMS were observed in the 229 equol nonproducers.

Investigators grouped all of the women into four levels of soy consumption. The four equol producer groups averaged 28.55, 14.2, 9.01 and 4.88 milligrams of daidzein per day (mg/d) and the average daidzein intake levels in the equol nonproducers were 28.69, 13.76, 8.98 and 4.63 mg/d, which is a range comparable to general soy consumption in Asians.

The researchers also used the Soy-Food Questionnaire to ask women about their diets. This validated tool, developed by Fred Hutchinson Cancer Research Center, poses questions about the consumption of 20 commonly eaten soy foods and supplements to assess soy intake among postmenopausal women in the United States.

The enrolled women averaged 53 years and more than 60 percent were postmenopausal.

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Otsuka Pharmaceutical Co. Ltd. supported the study. The complete data will be submitted to a peer-review journal for publication.

About Equol

S-Equol, produced in the intestine by bacteria converting daidzein to the compound, has the ability to bind to the same estrogen receptors as naturally estrogen, with a strong affinity to the estrogen receptor beta. On binding to these receptors, 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 of the symptoms caused by diminished estrogen production during menopause.

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 and a subsidiary of Otsuka, is studying the supplement containing S-equol for the management of menopausal symptoms.

NAMS Presentation

Friday, October 5, 2012 Oral Presentation S-23 Equol Producer Status and Self-Reported Vasomotor Symptoms Katherine M. Newton, PhD, of Group Health Research Institute; Susan D. Reed, MD, MPH, of the University of Washington; Conghui Qu, MS, and Johanna W. Lampe, PhD, RD, both of the Fred Hutchinson Cancer Research Center; Soh Iwashita, PhD of Otsuka Pharmaceuticals Co., Ltd. and Pharmavite LLC; Shigeto Uchiyama, MS , and Tomomi Ueno, MS, both of Otsuka Pharmaceuticals Co., Ltd.; and Johanna W. Lampe, PhD, RD.

About Pharmavite LLC:

For 40 years, Pharmavite has earned and maintained the trust of healthcare professionals, consumers, and retailers by manufacturing high-quality vitamins, minerals, herbs and other dietary supplements that are safe, effective and science-based. Nature Made® is the number one selling dietary supplement brand in the food, drug, club and mass channels. The dietary supplement industry is regulated by the U.S. Food and Drug Administration and the Federal Trade Commission, as well as by government agencies in each of the 50 states.

About Otsuka Pharmaceutical Co., Ltd.:

Founded in 1964, Otsuka Pharmaceutical Co., Ltd. is a global healthcare company with the corporate philosophy: ‘Otsuka-people creating new products for better health worldwide.’ Otsuka researches, develops, manufactures and markets innovative and original products, with a focus on pharmaceutical products for the treatment of diseases and consumer products for the maintenance of everyday health. Otsuka is committed to being a corporation that creates global value, adhering to the high ethical standards required of a company involved in human health and life, maintaining a dynamic corporate culture, and working in harmony with local communities and the natural environment. Otsuka Pharmaceutical Co., Ltd. is a wholly owned subsidiary of Otsuka Holdings Co., Ltd., the holding company for the Otsuka Group.

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