Other Name(s):

(3S)-3-(4-Hydroxyphenyl)-7-chromanol , 4',7-isoflavandiol, 7,4'-dihydroxy-isoflavan, 7-hydroxy-3-(4'-hydroxyphenyl)-chroman, SE5-OH, S-equol.


Equol comes from soy. When soy is eaten certain bacteria in the gut change chemicals contained in soy to equol. However, only 30-60% of people are able to break down soy chemicals to form equol. Some studies have shown that people capable of breaking soy down to form equol get more health benefits from soy. These people are called “equol producers.”

Equol is used for reducing menopause symptoms such as hot flashes in women. It is also used to prevent weak bones (osteoporosis) and to reduce wrinkled skin. Other uses include preventing metabolic syndrome, preventing diseases of the heart and blood vessels, treating high cholesterol, treating diabetes, and preventing breast and prostate cancer.

Equol comes in two different forms, R-equol or S-equol. Most commercial equol products contain S-equol.

How does it work?

Equol is a chemical that has some effects that are similar to the hormone estrogen, but it is much less potent than estrogen.

Uses & Effectiveness

Possibly Effective for...

  • Menopausal symptoms. Taking S-equol by mouth appears to improve symptoms related to menopause including hot flashes in women who cannot produce equol from soy.

Insufficient Evidence to Rate Effectiveness for...

More evidence is needed to rate the effectiveness of equol for these uses.

Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, and Insufficient Evidence to Rate (detailed description of each of the ratings).


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Side Effects

Taking equol supplements is LIKELY SAFE when used for up to one year. Equol can cause some mild side effects such as constipation, bloating, and dizziness. It can also cause allergic reactions involving rash in some people.

Special Precautions & Warnings

Pregnancy and breast-feeding: There isn't enough reliable information about the safety of taking equol if you are pregnant or breast feeding. Stay on the safe side and avoid use.

Breast Cancer: The effects of equol in people with breast cancer are unclear. Some research finds that equol might “feed” certain breast cancers because it can act like estrogen. Other studies have found that equol seems to protect against breast cancer. Because there isn't enough reliable information about the effects of equol in women with breast cancer, a history of breast cancer, or a family history of breast cancer, it is best to avoid using equol until more is known.


Birth control pills (Contraceptive drugs)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Some birth control pills contain estrogen. In the body, estrogen can either be free or it can be attached to certain proteins. The free estrogen is the type that works in the body. Equol might increase the amount of free estrogen. Taking equol along with birth control pills might increase the risk of side effects from the birth control pills. These side effects include headaches, breast tenderness, painful periods, and weight gain.

Some birth control pills include ethinyl estradiol and levonorgestrel (Triphasil), ethinyl estradiol and norethindrone (Ortho-Novum 1/35, Ortho-Novum 7/7/7), and others.

EstrogensInteraction Rating: Moderate Be cautious with this combination.Talk with your health provider.

In the body, estrogen can either be free or it can be attached to certain proteins. The free estrogen is the type that works in the body. Equol might increase the amount of free estrogen in the body. Taking equol along with estrogen might increase the risk of side effects from estrogen replacement therapy. These side effects include headaches, breast tenderness, and weight gain.

Some estrogen pills include conjugated equine estrogens (Premarin), ethinyl estradiol, estradiol, and others.

TestosteroneInteraction Rating: Moderate Be cautious with this combination.Talk with your health provider.

In the body, testosterone can either be free or it can be attached to certain proteins. The free testosterone is the type that works in the body. Equol might increase the amount of free testosterone in the body. Taking equol along with testosterone might increase the risk of side effects from testosterone replacement therapy. These side effects include acne, headaches, weight gain, and growth of breasts in men.

Water pills (Diuretic Drugs)Interaction Rating: Minor Be cautious with this combination.Talk with your health provider.

Equol has similar effects to "water pills." Taking equol along with "water pills" might increase the risk of side effects including low blood pressure, dizziness, and dehydration.

Some "water pills" include chlorothiazide (Diuril), chlorthalidone (Thalitone), furosemide (Lasix), hydrochlorothiazide (HCTZ, HydroDiuril, Microzide), spironolactone (Aldactone), and others.


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The following doses have been studied in scientific research:


  • For menopausal symptoms such as hot flashes: 10-40 mg per day in divided doses.
  • For preventing weak bones (osteoporosis): 10 mg per day.
  • For reducing skin wrinkles: 5 or 15 mg two times per day.
  • For metabolic syndrome: 10 mg per day.

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Reviewed on 6/14/2021

Woclawek-Potocka W, Bober A, Korzekwa A, et al. Equol and para-ethyl-phenol stimulate prostaglandin F(2alpha) secretion in bovine corpus luteum: intracellular mechanisms of action. Prostaglandins Other Lipid Mediat 2006;79:287-97. View abstract.

Alda JO, Mayoral JA, Lou M, et al. Purification and chemical characterization of a potent inhibitor of the Na-K-Cl cotransport system in rat urine. Biochem Biophys Res Commun 1996;221:279-85.

Arora A, Nair MG, Strasburg GM. Antioxidant activities of isoflavones and their biological metabolites in a liposomal system. Arch Biochem Biophys 1998;356:133-41. View abstract.

Aso T, Uchiyama S, Matsumura Y, et al. A natural S-equol supplement alleviates hot flushes and other menopausal symptoms in equol nonproducing postmenopausal Japanese women. J Womens Health (Larchmt) 2012;21:92-100. View abstract.

Aso T. Equol improves menopausal symptoms in Japanese women. J Nutr 2010;140:1386S-9S. View abstract.

Braidman IP, Hainey L, Batra G, et al. Localization of estrogen receptor beta protein expression in adult human bone. J Bone Miner Res 2001;16:214-20. View abstract.

Brown NM, Belles CA, Lindley SL, et al. The chemopreventive action of equol enantiomers in a chemically induced animal model of breast cancer. Carcinogenesis 2010;31:886-93. View abstract.

Chin-Dusting JP, Fisher LF, Lewis TV, et al. The vascular activity of some isoflavone metabolites: implications for a cardioprotective role. Br J Pharmacol 2001;133:595-605. View abstract.

Choe EJ. Chronic equol administration attenuates the antioxidant defense system and causes apoptosis in the mouse brain. Food Chem Toxicol 2009;47:1779-84. View abstract.

Choi EJ, Ahn WS, Bae SM. Equol induces apoptosis through cytochrome c-mediated caspases cascade in human breast cancer MDA-MB-453 cells. Chem Biol Interact 2009;177:7-11. View abstract.

Gimenez I, Lou M, Vargas F, et al. Renal and vascular actions of equol in the rat. J Hypertens 1997;15:1303-8. View abstract.

Goodman MT, Shvetsov YB, Wilkens LR, et al. Urinary phytoestrogen excretion and postmenopausal breast cancer risk: the multiethnic cohort study. Cancer Prev Res (Phila) 2009;2:887-94. View abstract.

Grace PB, Taylor JI, Low YL, et al. Phytoestrogen concentrations in serum and spot urine as biomarkers for dietary phytoestrogen intake and their relation to breast cancer risk in Euorpean prospective investigation of cancer and nutrition-norfolk. Cancer Epidemiol Biomarkers Prev 2004;13:698-708. View abstract.

Hodgson J, Croft K, Puddey I, et al. Soybean isoflavanoids and their metabolic products inhibit in vitro lipoprotein oxidation in serum. J Nutr Biochem 1996;7:664-9.

Hwang J, Wang J, Morazzoni P, et al. The phytoestrogen equol increases nitric oxide availability by inhibiting superoxide production: an antioxidant mechanism for cell-mediated LDL modification. Free Radic Biol Med 2003;34:1271-82. View abstract.

Ingram D, Sanders K, Kolybaba M, Lopez D. Case-control study of phyto-oestrogens and breast cancer. Lancet 1997;350-:990-4. View abstract.

Ishiwata N, Melby MK, Mizuno S, Watanabe S. New equol supplement for relieving menopausal symptoms: randomized, placebo-controlled trial of Japanese women. Menopause 2009;16:141-8. View abstract.

Jackman KA, Woodman OL, Chrissobolis S, Sobey CG. Vasorelaxant and antioxidant activity of the isoflavone metabolite equol in carotid and cerebral arteries. Brain Res 2007;1141:99-107. View abstract.

Jackson RL, Greiwe JS, Desai PB, Schewn RJ. Single-dose and steady-state pharmacokinetic studies of S-equol, a potent nonhormonal, estrogen receptor ß agonist being developed for the treatment of menopausal symptoms. Menopause 2011;18:185-93. View abstract.

Jackson RL, Greiwe JS, Schwen RJ. Emerging evidence of the health benefits of S-equol, an estrogen receptor ß agonist. Nutr Rev 2011;69:432-48. View abstract.

Jenks BH, Iwashita S, Nakagawa Y, et al. A pilot study on the effects of S-equol compared to soy isoflavones on menopausal hot flash frequency. J Womens Health (Larchmt) 2012;21:674-82. View abstract.

Joy S, Siow RC, Rowlands DJ, et al. The isoflavone equol mediates rapid vascular relaxation: Ca2+-independent activation of endothelial nitric-oxide synthase/Hsp90 involving ERK1/2 and Akt phosphorylation in human endothelial cells. J Biol Chem 2006;281:27335-45. View abstract.

Ju YH, Fultz J, Allred KF, et al. Effects of dietary daidzein and its metabolite, equol, at physiological concentrations on the growth of estrogen-dependent human breast cancer (MCF-7) tumors implanted in ovariectomized athymic mice. Carcinogenesis 2006;27:856-63. View abstract.

Kelly AJ, Malik S, Smith L, et al. Vaginal prostaglandin (PGE2 and PGF2a) for induction of labour at term. Cochrane Database Syst Rev 2009;4:CD003101. View abstract.

Lund TD, Munson DJ, Haldy ME. Equol is a novel anti-androgen that inhibits prostate growth and hormone feedback. Biol Reprod 2004;70:1188-95. View abstract.

Martin ME, Haouriqui M, Pelissero C, et al. Interactions between phytoestrogens and human sex steroid binding protein. Life Sci 1996;58:429-36. View abstract.

Martinez RM, Gimenez I, Lou JM, et al. Soy isoflavonoids exhibit in vitro biological activities of loop diuretics. Am J Clin Nutr 1998;68:1354S-57S. View abstract.

Mitchell JH, Gardner PT, McPhail DB, et al. Antioxidant efficacy of phytoestrogens in chemical and biological model systems. Arch Biochem Biophys 1998;360:142-8. View abstract.

Morito K, Hirose T, Kinjo J, et al. Interaction of phytoestrogens with estrogen receptors alpha and beta. Biol Pharm Bull 2001;24:351-6. View abstract.

Mueller SO, Simon S, Chae K, et al. Phytoestrogens and their human metabolites show distinct agonistic and antagonistic properties on estrogen receptor alpha (ERalpha) and ERbeta in human cells. Toxicol Sci 2004;80:14-25. View abstract.

Oyama A, Ueno T, Uchiyama S, et al. The effects of natural S-equol supplementation on skin aging in postmenopausal women: a pilot randomized placebo-controlled trial. Menopause 2012;19:202-10. View abstract.

Setchell KD, Brown NM, Lydeking-Olsen E. The clinical importance of the metabolite equol-a clue to the effectiveness of soy and its isoflavones. J Nutr 2002;132:3577-84. View abstract.

Setchell KD, Clerici C, Lephart ED, et al. S-equol, a potent ligand for estrogen receptor beta, is the exclusive enantiomeric form of the isoflavone metabolite produced by human intestinal bacterial flora. Am J Clin Nutr 2005;81:1072-9. View abstract.

Setchell KD, Clerici C. Equol: history, chemistry, and formation. J Nutr 2010;140:1355S-62S. View abstract.

Setchell KD, Clerici C. Equol: pharmacokinetics and biological actions. J Nutr 2010;140:1363S-8S. View abstract.

Shi J, Ji A, Cao Z, et al. Equol induced apoptosis of human breast cancer MDA-MB-231 cell by inhibiting the expression of nuclear factor-kappaB. Wei Sheng Yan Jiu 2011;40:95-8. View abstract.

Tousen Y, Ezaki J, Fujii Y, et al. Natural S-equol decreases bone resorption in postmenopausal, non-equol-producing Japanese women: a pilot randomized, placebo-controlled trial. Menopause 2011;18:563-74. View abstract.

Usui T, Tochiya M, Sasaki Y, et al. Effects of natural S-equol supplements on overweight or obesity and metabolic syndrome in the Japanese, based on sex and equol status. Clin Endocrinol (Oxf) 2013;78:365-72. View abstract.

Vedevanam K, Srijayanta S, O'Reilly J, et al. Antioxidant action and potential antidiabetic properties of an isoflavonoid-containing soyabean phytochemical extract (SPE). Phytother Res 1999;13:601-8. View abstract.

Woclawek-Potocka I, Borkowski K, Korzekwa A, et al. Phyto- and endogenous estrogens differently activate intracellular calcium ion mobilization in bovine endometrial cells. J Reprod Dev 2006;52:731-40. View abstract.

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