SubEx

Body compound · C15H14O3

Equol (S-equol)

Made in your gut from soy, by bacteria not everyone carries. The split is real, the supplement does something small, and the link between them is untested.

Findings
4
Best evidence
★★☆
Open questions
3

At a glance

Myth check

Soy only works if your gut can turn it into equol, so find out whether you are an equol producer, and if you are not, buy the equol directly.

The producer split is real and measurable. The paper that set the standard test found 59 percent of 29 vegetarians and 25 percent of 12 non-vegetarians were producers, and noted the vegetarian figure resembles reported frequencies in Japanese adults eating soy. Those group sizes are small, and the widely repeated claim that about a quarter to a third of Western adults are producers is consistent with this study rather than established by it. Equol taken directly does something. In 160 postmenopausal Japanese women selected for being non-producers, 10 mg a day for twelve weeks cut hot flushes by 1.9 a day against 1.0 a day on placebo, from a starting point of about three a day. That is a real difference of about nine-tenths of one flush a day, and the placebo group improved by a third on its own. What has not been shown is the step the story depends on: that being a producer makes soy itself work better. The 2023 North American Menopause Society statement does not recommend equol for hot flushes.

The metabolic split is real, the supplement does something small, and the link between the two is the part nobody has demonstrated.

The findingsStrongest first
1
OtherWhether you make equol depends on the bacteria in your gut

It is made from daidzein, one of soy's isoflavones, by gut bacteria. In the study that set the standard test, 59 percent of 29 vegetarians could and 25 percent of 12 others.

★★☆Single study — solid evidence, such as one good trial or a large observational dataset, but not replicated at the top tier.Twenty-five percent of twelve people is three people, so the familiar claim that a quarter to a third of Westerners are producers is consistent with this study rather than established by it. Its lasting contribution is the test, not the prevalence, and the work was done at a company that sells soy.Click to keep this openBalance hormones
2?
OtherNobody has tested whether making equol changes what soy does

The trial usually cited gave equol directly to women who could not make it. The producer-split study measured who could convert, not who responded.

★☆☆Contested — the evidence disagrees with itself, or the finding carries a caution. A caution or conflict always shows one star, however strong the sources are.CautionThis states what these two studies were built to measure, not that no such comparison exists anywhere in the wider literature. Both are small: 160 women in the trial, and 41 in the producer-status study, of whom 12 were non-vegetarians.Click to keep this openBalance hormones
3↓
Sexual & reproductiveEquol took hot flushes down by 1.9 a day; placebo took them down 1.0

In 160 postmenopausal Japanese women who cannot make equol themselves, 10 mg a day for twelve weeks moved flushes from a starting point of about three a day.

★☆☆Contested — the evidence disagrees with itself, or the finding carries a caution. A caution or conflict always shows one star, however strong the sources are.Conflicting evidenceEveryone enrolled started low, at about three flushes a day, and one a day was enough to take part, so the percentage figures the trial reports describe small absolute movements. Thirty-four of the 160 randomised did not finish, and the reported analysis is of those who did. Japanese women only.Click to keep this openBalance hormones
4
OtherA menopause society does not recommend soy for hot flushes

Its 2023 statement lists soy foods, soy extracts and equol among treatments it does not recommend. The grade means limited or inconsistent evidence, not proof of no effect.

★☆☆Contested — the evidence disagrees with itself, or the finding carries a caution. A caution or conflict always shows one star, however strong the sources are.Conflicting evidenceA position statement inherits whatever its panel weighted, and produces no new estimates of its own. The recommendation covers hot flushes and night sweats only, and says nothing about soy for bone, cholesterol or cancer outcomes.Click to keep this openBalance hormones
Sources3 behind this page

Taken with something else

What the evidence says about combining Equol (S-equol) with each of these. The marker is how well established the interaction is; a caution is about the hazard, which is a different question.

What we don't know

3 open questions