Equol is a nonsteroidal estrogen metabolite produced by intestinal bacteria from the soy isoflavone daidzein. Not everyone can naturally produce equol, but research has focused on the use of proprietary equol supplements to alleviate menopausal symptoms, particularly hot flashes. Several randomized, placebo-controlled trials have demonstrated that supplementation with S-equol (the biologically active enantiomer) can significantly reduce the frequency and severity of hot flashes in peri- and postmenopausal women compared to placebo. For example, studies published in journals such as Menopause and Maturitas (e.g., Ishiwata et al., 2009; Aso et al., 2012) have shown moderate reductions in vasomotor symptoms with daily S-equol supplementation over 8-12 weeks.

The mechanism appears to involve S-equol’s selective estrogen receptor modulator (SERM)-like activity, exhibiting a preference for estrogen receptor beta, which is thought to be involved in thermoregulation and may explain the reduction in hot flashes. While the quality of the evidence is generally moderate—limited by sample sizes and study durations—the outcomes are consistent and clinically relevant. There is no longstanding traditional use of isolated equol itself; its use is grounded primarily in modern scientific research and the understanding of isoflavone metabolism. Thus, while more extensive studies could further clarify its efficacy, current evidence supports the use of proprietary equol to manage hot flashes, especially in women who do not naturally produce equol.