Equol, a product of intestinal metabolism of daidzein, is chemically similar to estrogen (without the lipophilic moiety) and has higher estrogen receptor-beta binding affinity than its parent precursor. In 2004, a long-term, randomized controlled trial that characterized postmenopausal women by their equol-producing status showed stronger advantages to lumbar spine bone mineral density (BMD) in equol- compared with nonequol-producers. Subsequent studies have related equol status of participants to change in bone turnover markers or BMD in response to soy isoflavone interventions. To our knowledge, we are the first to prescreen women for equol-producing status prior to initiating an intervention. In menopausal Western women, equol status did not affect the modest, but significant, reduction in bone resorption achieved with a soy isoflavone intervention.