Soy is commonly used to support menopausal symptoms, particularly hot flashes and night sweats, due to its content of isoflavones—plant-derived compounds with weak estrogenic activity. Scientific interest in soy for menopause arose from epidemiological observations that women in East Asian countries, where soy intake is high, tend to report fewer and less severe vasomotor symptoms compared to women in Western countries. Isoflavones such as genistein and daidzein can bind to estrogen receptors and exert mild estrogen-like effects, potentially mitigating the decline in endogenous estrogen during menopause.

Randomized controlled trials and meta-analyses have shown mixed but generally modest benefits. Some studies report a reduction in the frequency and severity of hot flashes, with effects typically smaller than those achieved with hormone replacement therapy. The North American Menopause Society acknowledges that isoflavones may be "modestly effective" for managing vasomotor symptoms. However, variability in response may depend on individual metabolism and the type, dose, and duration of soy consumption. Safety profiles are generally favorable for short-term use.

In summary, while soy is not a cure-all, its use for menopausal symptoms is supported by plausible biological mechanisms and moderate-quality clinical evidence, rating about a 3 on a 0-5 scale for efficacy.