What does equol from soy do for women after menopause?
Equol from soy shows a reduction in hot flushes and a slowing of bone loss after menopause. The strongest evidence applies to women with frequent hot flushes or to women who do not produce equol from soy themselves, with daily supplementation of 10 to 40 mg of S-equol being the most studied approach.
Hot flushes are the most studied application. Five studies combined show that equol supplementation reduces the frequency and severity of hot flushes, but two of those five found no clear effect. The picture is therefore encouraging, not conclusive. A smaller eight-week study (102 women) compared direct equol tablets with soy isoflavones: 20 to 40 mg of S-equol per day worked better in women who had more than eight hot flushes per day. At 10 mg per day it was comparable to regular soy isoflavones.
The results for bones are notable. Women who produce equol themselves from soy isoflavones lost noticeably less bone density in the hip over one year than women who do not produce equol: -0.46% versus -2.28%. A separate treatment study with 10 mg of S-equol per day also showed a clear reduction in a measurable marker of bone breakdown in the urine, compared with a dummy treatment. Whether this leads to fewer fractures has not yet been studied.
Muscle and joint pain after menopause decreased noticeably in that same small comparative study at 10 and 20 mg of S-equol per day, more so than with soy isoflavones. This is still only one study, so it is too early to draw firm conclusions.
For mood, one study showed improvement at 30 mg per day, specifically in women who do not naturally produce equol. For the heart and blood vessels, equol itself has no demonstrable advantage over other isoflavones: isoflavones reduced an inflammation marker in the blood but had no effect on cholesterol or blood sugar, and whether or not someone produces equol made no difference here.
Safety data are limited but reassuring so far: after one year of use at 10 mg of S-equol per day, sex and thyroid hormone levels did not change and no side effects were reported. This comes from a small study in Japanese women; little is known about long-term use in other populations. If you want to use equol as a supplement alongside medicines, discuss this with your doctor.
This answer draws on five controlled studies and two reviews combining many studies with pooled analyses. The controlled studies are mostly small (one Japanese treatment study, one comparative study of 102 women) and short in duration. The pooled analysis on hot flushes included 728 participants but also counted two studies that found no effect, which makes the conclusion less definitive. The researchers considered the evidence limited or moderate in most areas; for bone density and hot flushes the evidence is strongest, but still not large enough to base firm clinical recommendations on.