Neuroprotection by Dietary Isoflavones and Their Role in Cerebral Ischemia

Dietary isoflavones derived from soybeans and other legumes have long been part of the Asian diet and are considered a safe, healthy protein source. More recently, the estrogenic nature of isoflavones has been explored for postmenopausal symptoms in women with equivocal results. However, the beneficial effects of dietary isoflavones in the brain have received new attention with the recognition that these compounds can be neuroprotective in experimental cerebral ischemia and other models of neurodegenerative diseases, such as Alzheimer's disease. Several overlapping mechanisms likely underlie these protective mechanisms, including transcriptional activation by estrogen receptors and multiple antioxidant effects on the mitochondria. These generalized mechanisms support all members of the neurovascular unit and may provide both prophylactic and acute neuroprotection. Human studies support a role for soy isoflavones in cardiovascular health, but the neuroprotective properties of isoflavones in humans are yet to be elucidated.