Phytoestrogens and cognitive function: a review.
Neuroprotective effects of phytoestrogen compounds (found in soy) have been demonstrated in animal research and cell culture studies. In particular, phytoestrogens have been shown to reduce Alzheimer's Disease (AD) related pathology, potentially alleviating risk of AD progression. In addition to their antioxidant properties, soy products also have the ability to affect cognition via interaction with estrogen receptors. However, observational studies and randomised controlled trials in humans have resulted in inconclusive 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 European cohorts, with an average low dietary consumption. In contrast, investigation of Asian populations, with a higher general intake of tofu (a non-fermented soy product) have shown negative associations with cognitive function in those over the age of 65. Consideration of type of soy product is important, as in the latter sample, protective effects of tempe (fermented soy) were also observed. Limited data provide evidence that effects of phytoestrogens on cognition may be modified by dosage, duration of consumption and cognitive test used. Additionally, characteristics of the study population including age, gender, ethnicity and menopausal status appear to be mediating variables. Phytoestrogen treatment interventions have also shown time-limited positive effects on cognition. These findings are consistent with estrogen treatment studies, where initial positive short-term cognitive effects may occur, which reverse with long-term continuous use in elderly women. Well controlled, large scale studies are needed to assess the effects of phytoestrogens on the aging brain and provide further understanding of this association.
School of Sport, Exercise and Health Sciences, Loughborough University, United Kingdom. Electronic address: M.Soni@lboro.ac.uk.
Mira
M
Soni
Department of Public Health, Respati University Yogyakarta, Indonesia.
Tri Budi W
TB
Rahardjo
Department of Public Health, Respati University Yogyakarta, Indonesia.
Rodiyah
R
Soekardi
Department of Public Health, Respati University Yogyakarta, Indonesia.
Yenny
Y
Sulistyowati
Department of Public Health, Respati University Yogyakarta, Indonesia.
Lestariningsih
Centre for Outcomes Research and Effectiveness, Research Department of Clinical, Educational and Health Psychology, University College London, 1-19 Torrington Place, W1CE 4HB, UK.
Amina
A
Yesufu-Udechuku
Department of Nutrition, University of Bogor, Bogor Indonesia.
Atik
A
Irsan
School of Sport, Exercise and Health Sciences, Loughborough University, United Kingdom; Department of Public Health, Respati University Yogyakarta, Indonesia.
Eef
E
Hogervorst
D000544:Alzheimer Disease / Q000178:diet therapy* / Q000188:drug therapy; D001921:Brain / Q000187:drug effects*; D003071:Cognition / Q000187:drug effects*; D003072:Cognition Disorders / Q000517:prevention & control*; D005260:Female; D006801:Humans; D007529:Isoflavones / Q000494:pharmacology / Q000627:therapeutic use*; D008297:Male; D008568:Memory / Q000187:drug effects; D018696:Neuroprotective Agents / Q000494:pharmacology / Q000627:therapeutic use; D048789:Phytoestrogens / Q000494:pharmacology* / Q000627:therapeutic use; D013025:Glycine max / Q000737:chemistry*
D007529:Isoflavones; D018696:Neuroprotective Agents; D048789:Phytoestrogens
Aging; Cognition; Dementia; Isoflavone; Phytoestrogen; Soy