Yokosuka K, Rutledge C, Kamio Y, et al. - This study was undertaken to determine if the isoflavones daidzein and equol are protective against the formation and rupture of intracranial aneurysms in a mouse model of the postmenopausal state. The authors used a combination of induced systemic hypertension and a single injection of elastase into the cerebrospinal fluid to induce intracranial aneurysms in ovariectomized adult female mice. The findings show that dietary daidzein and its metabolite, equol, protect against aneurysm formation in ovariectomized female mice by activating estrogen receptor-β and suppressing inflammation. The protective effect of dietary daidzein required intestinal conversion to equol. The findings point to the potential therapeutic value of dietary daidzein and its metabolite, equol, in the prevention of intracranial aneurysm formation and related subarachnoid hemorrhage.