Soy isoflavones are phytoestrogens—plant-derived compounds with estrogen-like activity. Their use to support the female reproductive system, particularly for alleviating menopausal symptoms such as hot flashes and night sweats, is supported by a moderate body of scientific evidence. Several randomized controlled trials and meta-analyses have shown that soy isoflavone supplementation can modestly reduce the frequency and severity of vasomotor symptoms in menopausal women. The mechanism is believed to be their ability to bind to estrogen receptors, exerting weak estrogenic or anti-estrogenic effects depending on endogenous estrogen levels.

However, the efficacy of soy isoflavones is variable among individuals, partially due to differences in gut microbiota that affect isoflavone metabolism. Some studies have not found significant benefits, leading to a moderate (rather than strong) overall evidence rating. There is less robust evidence supporting the use of soy isoflavones for other female reproductive system concerns, such as menstrual regulation or fertility. Safety profiles are generally favorable for short-term use, but long-term effects are still being studied.

In summary, while soy isoflavones have a basis in scientific research for supporting the female reproductive system—mainly for menopause symptom relief—the strength and consistency of evidence are moderate, not definitive.