Association of Urinary Equol Concentration with Frailty in Community-Dwelling Older Adults: The Itabashi Longitudinal Study on Aging

Background: Frailty is a common geriatric syndrome associated with adverse health outcomes. Equol, a metabolite of the soy isoflavone daidzein, has gained attention for its potential health benefits, particularly in bone, muscle, and cardiovascular health. This study examines the association between urinary equol concentration and frailty status in older adults, with participants further classified into equol producers and non-producers. Methods: A cross-sectional analysis was conducted using data from 651 community-dwelling older adults (aged 70-85) participating in the Itabashi Longitudinal Study on Aging in February 2023. Urinary equol concentration was measured using Enzyme-Linked Immunosorbent Assay, and participants were classified as equol producers (≥1,000 nmol/L) or non-producers (