Phytoestrogens and cognitive function: a review


Neuroprotective effects of phytoestrogen compounds (found in soy) have been demonstrated in animalresearch and cell culture studies. In particular, phytoestrogens have been shown to reduce Alzheimer’sDisease (AD) related pathology, potentially alleviating risk of AD progression. In addition to their antiox-idant properties, soy products also have the ability to affect cognition via interaction with estrogenreceptors. However, observational studies and randomised controlled trials in humans have resulted ininconclusive findings within this domain. There are several possible reasons for these discrepant data.Studies which report no effect of phytoestrogens on cognition have mainly been carried out in Europeancohorts, with an average low dietary consumption. In contrast, investigation of Asian populations, witha higher general intake of tofu (a non-fermented soy product) have shown negative associations withcognitive function in those over the age of 65. Consideration of type of soy product is important, as in thelatter sample, protective effects of tempe (fermented soy) were also observed. Limited data provide evi-dence that effects of phytoestrogens on cognition may be modified by dosage, duration of consumptionand cognitive test used. Additionally, characteristics of the study population including age, gender, eth-nicity and menopausal status appear to be mediating variables. Phytoestrogen treatment interventionshave also shown time-limited positive effects on cognition. These findings are consistent with estro-gen treatment studies, where initial positive short-term cognitive effects may occur, which reverse withlong-term continuous use in elderly women. Well controlled, large scale studies are needed to assess theeffects of phytoestrogens on the aging brain and provide further understanding of this association.© 2014 Elsevier Ireland Ltd. All rights reserved


Reviewer 1

Reviewer 2