Studies examining the efficacy of soy-based dietary supplements for menopausal hot flashes and night sweats have shown mixed results (e.g., modest to no benefit). Here’s an interesting fact that might explain why! Some women convert the soy-based constituent, daidzein (an isoflavone), to equol (a metabolite with estrogen-like activity). Typically women of Asian or Hispanic background make the conversion and are more likely to experience positive results from a soy-based supplement for their flashes. However, many women do not make this conversion. For the latter group, it would not matter what soy-based dietary supplement they consumed as none would be expected to work.
If you are peri-menopausal and experiencing hot flashes, instead of taking a soy-based dietary supplement, consider adding a 1-2 servings each day of tofu, soy milk, edamame, or a soy-based protein powder for a few months to see if any of these foods/products make a difference.
If you have a history of hormone-dependent cancer (especially estrogen receptor-positive breast cancer) please refrain from consuming soy-based foods, products, or dietary supplements for any reason unless your physician has first given you permission to do so. If you are in the cancer risk category and are suffering from hot flashes that impair your lifestyle, please talk with your physician about the appropriateness of one of several other prescription options including venlafaxine, paroxetine, of clonidine. Hang in there and keep a positive attitude as best you can. This too shall pass – typically within 6 months to 2 years for most women!