Research
Soy isoflavones for Menopause: Evidence, Interactions and Cautions
Soy isoflavones is an ingredient used in menopause supplements marketed to women. Below is what it has actually been studied for, how strong that evidence is, the drug interactions and cautions on record, and the primary source our grade rests on — all drawn from the HerWellReport ingredient dataset.
Also sold as: Glycine max isoflavones; genistein; daidzein; soy extract
What the evidence says about Soy isoflavones
The Cochrane review of phytoestrogens covered 43 trials in 4,084 women and found no conclusive evidence that phytoestrogen supplements reduce the frequency or severity of hot flushes and night sweats, although four trials of extracts providing more than 30 mg a day of genistein did consistently reduce hot flush frequency. Many of the included trials were small, short and at high risk of bias, and the preparations varied widely, so a genuine effect of concentrated genistein cannot be ruled out or confirmed. The Menopause Society's 2023 nonhormone therapy position statement names soy foods and soy extracts on its not-recommended list (Level II), calling the findings mixed. NCCIH notes soy foods appear safe for breast cancer survivors but that the safety of concentrated supplements is uncertain.
The grade "limited for hot flushes; none for stress incontinence" means: limited — One or two small human trials, or trials for a closely related outcome. none — No human trial evidence we could find for this use. Grades are explained in full on our methodology page.
Read the primary source this grade rests on (opens in a new tab).
Soy isoflavones drug interactions
- tamoxifen
- aromatase inhibitors
- levothyroxine
Who should be careful with Soy isoflavones
- Talk to your oncologist before using concentrated isoflavone supplements if you have or have had a hormone-sensitive cancer
- long-term supplement use has been linked to thickening of the womb lining
- avoid if you are allergic to soy
Read more on HerWellReport
- Best Menopause Supplements: What Is Actually In Them
- Happy Mammoth Hormone Harmony Review: The Claims a Regulator Told Them to Drop
- Swanson Go-Less Bladder Control Review: What’s Actually in It, and How the Dose Compares to AZO
- One A Day Women’s Menopause Formula: An Honest Ingredient Review
- MenoRescue vs Provitalize: Ingredients, Price and Guarantee Compared
This entry is generated from row "Soy isoflavones" of the HerWellReport ingredient dataset (v2.1, updated 2026-09-23). The dataset is free to reuse under CC BY 4.0 — how to cite it. Ingredient evidence is not evidence for any finished product, and nothing here is medical advice.