Reviewed on 6/11/2021
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.


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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).

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.


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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.


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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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.

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