Equol Nonproducing Status as an Independent Risk Factor for Acute Cardioembolic Stroke and Poor Functional Outcome

<b>Background/Objectives</b>: Equol has protective effects against coronary artery disease and dementia by strongly binding to estrogen receptor beta, whereas the intake of soy isoflavone alone does not always confer such protective effects. Equol production is completely dependent on the existence of equol-producing gut microbiota. The effects of equol-producing status on the cerebrovascular diseases remain unclear. The current study was aimed to investigate the association of equol-producing status with the development of stroke and its neurological prognosis. <b>Methods</b>: Frequencies of equol producers were compared between healthy subjects (HS) registered in the Suita Study and patients with acute stroke admitted to our stroke center from September 2019 to October 2021 in a retrospective cohort study. <b>Results</b>: The proportion of HSs and patients with ischemic stroke who were equol producers did not significantly differ (50/103 [48.5%] vs. 60/140 [42.9%], <i>p</i> = 0.38). However, cardioembolic stroke was significantly associated with low a prevalence of equol producers (adjusted odds ratio [aOR] 0.46, 95% confidence interval [CI] 0.21-0.99, <i>p</i> = 0.05). A higher left atrial volume index was observed in equol nonproducers (46.3 ± 23.8 vs. 36.0 ± 11.6 mL/m², <i>p</i> = 0.06). The equol nonproducers had a significantly higher prevalence of atrial fibrillation than the equol producers (27.5% vs. 13.3%, <i>p</i> = 0.04). Furthermore, the equol producers exhibited a significantly favorable functional outcome upon discharge (aOR 2.84, 95% CI 1.20-6.75, <i>p</i> = 0.02). <b>Conclusions</b>: Equol is a promising candidate for interventions aiming to reduce the risk of CES and atrial dysfunction, such as atrial fibrillation and improve neurological prognosis after ischemic stroke.