Soy Reduces Menopausal Symptoms Among Equol Producers

phytoestrogens and menopause

Photo by Dan Klimke

By Case Adams, Naturopath

Researchers from the Czech Republic’s Mlada Regional Hospital in Boleslav have confirmed that consuming phytoestrogens decreases menopausal symptoms among women, but only among those who maintain particular intestinal probiotics that produce an isoflavone metabolite called S-equol.

Higher circulating levels of S-equol have been linked to decreases in bone loss, reduced prostate cancer and reduced menopausal symptoms, including hot flushes, night sweats and irritability. Some research has also indicated that S-equol reduces the risk of breast cancer and endometrial cancer.

The Czech study tested 28 menopausal women. They were given 80 milligrams of phytoestrogens daily while being tested for S-equol within their urine and bloodstream. Prior to the study, the researchers identified the “S-equol producers” versus “S-equol non-producers.”

Equol producers have better results from isoflavones

Among the S-equol producers, their S-equol urine levels went from 0.34 to 10.67 ng/ml after the isoflavone supplementation, while the non-producers’ levels went from 0.29 to a scant 0.34.

Meanwhile, Kupperman index ratings decreased substantially, but only for the S-equol producers. In the producers, Kupperman index values went from 23.44 to 14.44, while there was little change among the non-producers.

The Kupperman index measures hot flushes, insomnia, nervousness, melancholia, vertigo, weakness, arthralgia or myalgia (muscle pain), headache, paresthesia (tingling sensations), palpitations (quickening heart beats), and formication (skin sensations). A reduction in the index indicates reduced menopausal symptoms.

Equol is produced by probiotics after isoflavone consumption

S-equol (4′,7-isoflavandiol) – also called 5-hydroxy-equol – is produced by intestinal probiotics after they consume the isoflavones daidzein and genistein we eat. (Some have proposed that S-equol only comes from daidzein but recent research clearly indicates that certain probiotics will produce S-equol from genistein).

Isoflavones daidzein and genistein are a component of a number of foods, including asparagus; many types of beans including soybeans, fava beans, lupins, mung beans and lentils; seeds such as sesame, linseed and flax; and yams, apples, pomegranates, whole wheat and some others. Isoflavone-rich herbs include black cohosh, licorice root, fennel, anise, hops and chaste berry.

Other studies link isoflavones with reduced menopausal symptoms

The Czech Republic research confirms other studies that have shown lower menopausal symptoms among those consuming isoflavones. In one, 96 menopausal Taiwanese women were given 135 milligrams of isoflavones daily for six months. The isoflavone group reported significantly decreased menopausal symptoms. But again, this effect was only among those who were S-equol producers.

Equol production depends upon intestinal probiotics

This of course points to the health of our intestinal probiotics. Can probiotic supplements help increase S-equol levels? The research has indicated that many of the strains in our probiotic supplements do not increase S-equol production.

In a 2004 study from the University of Minnesota, isoflavone supplementation plus Lactobacillus acidophilus DDS+1 and Bifidobacterium longum did not generally increase S-equol production among a group of 20 women compared to controls (isoflavones alone). However, S-equol production went up significantly amongst a few of the women. The researchers concluded that, “the large differences between plasma and urinary equol in some subjects suggest that equol producer status may be modifiable in some individuals.”

However, in a 2011 study from Italy with twelve menopausal women, Lactobacillus sporogenes supplementation resulted in a 24% increase in genistein-related equol, while daidzein metabolite equol production only went up for some of the women but not all.

Another 2011 laboratory study indicated that Lactobacillus rhamnosus may increase daidzein S-equol production.

But a more recent study from Germany’s Institute of Human Nutrition published in January’s issue of the Journal of Nutrition has found that the intestinal probiotic bacteria (conveniently) named Slackia isoflavoniconvertens will convert both genistein and daidzein to 5-hydroxy-equol.


So while the hunt for the right combination of probiotics to turn “non-equol producers” into “S-equol producers” continues, there is good reason to believe that stronger resident probiotic colonies relate directly to S-equol production.

This means the subsequent health benefits related to higher circulating S-equol levels – which include cancer protection, bone health and lower menopausal symptoms – relate directly to healthy intestinal probiotics.

Learn how probiotics can boost health and prevent disease.

Matthies A, Loh G, Blaut M, Braune A. Daidzein and genistein are converted to equol and 5-hydroxy-equol by human intestinal Slackia isoflavoniconvertens in gnotobiotic rats. J Nutr. 2012 Jan;142(1):40-6.

Bicíková V, Sosvorová L, Bradác O, Pán M, Bicíková M. Phytoestrogenes in menopause: working mechanisms and clinical results in 28 patients. Ceska Gynekol. 2012 Feb;77(1):10-4.

Benvenuti C, Setnikar I. Effect of Lactobacillus sporogenes on oral isoflavones bioavailability: single dose pharmacokinetic study in menopausal women. Arzneimittelforschung. 2011;61(11):605-9.

Tamura M, Hori S, Nakagawa H. Lactobacillus rhamnosus JCM 2771: impact on metabolism of isoflavonoids in the fecal flora from a male equol producer. Curr Microbiol. 2011 May;62(5):1632-7.

Nettleton JA, Greany KA, Thomas W, Wangen KE, Adlercreutz H, Kurzer MS. Plasma phytoestrogens are not altered by probiotic consumption in postmenopausal women with and without a history of breast cancer. J Nutr. 2004 Aug;134(8):1998-2003.

Jou HJ, Wu SC, Chang FW, Ling PY, Chu KS, Wu WH. Effect of intestinal production of equol on menopausal symptoms in women treated with soy isoflavones. Int J Gynaecol Obstet. 2008 Jul;102(1):44-9.

Case Adams is a California Naturopath with a PhD in Natural Health Sciences, and Board Certified Alternative Medicine Practitioner. He has authored 26 books on natural healing strategies. “My journey into writing about alternative medicine began about 9:30 one evening after I finished with a patient at the clinic I practiced at over a decade ago. I had just spent the last two hours explaining how diet, sleep and other lifestyle choices create health problems and how changes in these, along with certain herbal medicines and other natural strategies can radically yet safely turn ones health around. As I drove home that night, I realized I needed to get this knowledge out to more people. So I began writing about health with a mission to reach those who desperately need this information. The strategies in my books and articles are backed by scientific evidence along with wisdom handed down through traditional medicines for thousands of years.” Case connects with the elements by surfing, hiking and being a beach bum.

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