Do soy and isoflavones help hot flashes?

Our verdict: Not recommended as a clinical treatment for hot flashes (Level II).

Soybeans contain plant compounds called isoflavones (such as genistein and daidzein) that bind weakly to estrogen receptors, and some people have gut bacteria that convert daidzein into S-equol. However, after reviewing the randomized trial literature in its 2023 Nonhormone Therapy Position Statement, The Menopause Society placed soy foods and extracts, as well as equol, in the not recommended category for treating hot flashes (Level II).

Nuance: whole food nutrition vs hot flash pills

As noted in our source registry, "not recommended" in the 2023 guideline means the evidence is too inconsistent or modest to recommend soy isoflavones or equol as an effective therapy for vasomotor symptoms. A 2013 Cochrane systematic review of 43 trials across all major phytoestrogen types reached the same conclusion, while also noting a strong placebo effect of 1% to 59% reduction that likely explains why these supplements can feel effective in everyday use. See our red clover verdict for how that specific extract fared in the same review.

Enjoying whole soy foods (such as tofu, tempeh, or edamame) as part of a nutritious diet is very different from buying concentrated over-the-counter isoflavone capsules expecting prescription-level relief.

If you have a personal history of hormone-sensitive breast cancer, always check with your oncologist before taking any concentrated phytoestrogen or isoflavone supplement.

Proven options to compare instead

• Menopausal hormone therapy (HRT): Most effective option for moderate-to-severe vasomotor symptoms in women without contraindications.
• Level I non-hormonal treatments: Including CBT, clinical hypnosis, SSRIs/SNRIs, gabapentin, and NK3 antagonists.
• Use our Does it work? evidence checker and browse the Does It Work? hub to see every graded remedy.