Soy, Tofu and Brain Function in the Elderly

Abstract

Tofu is regarded by some as a ‘superfood’ and many positive health benefits are attributed to its consumption, which is high is the East and on the increase in the West. Animal and cell culture studies suggest that phytoestrogens, abundant in soy products such as tempe and tofu, could protect the aging brain. With dementia prevalence increasing due to an aging population, these findings need confirmation in humans. Some observational studies have reported no effects of phytoestrogen consumption on cognitive function (Kreijkamp-Kaspers et al. 2007; Franco et al. 2005), but these findings were mainly in low-intake populations. However, other observational studies in Asian populations, which are characterized by a high average intake of tofu, have reported a negative association with cognitive function in those over 65 years of age (Rice et al. 2000; White et al. 2000). Similarly, in an Indonesian cohort of 719 elderly, we found that participants over 68 years of age who consumed tofu daily or more had worse memory function and a greater risk of dementia. It is unclear whether this association could be attributed to potential toxins added to tofu or to tofu’s phytoestrogens levels. On the other hand, phytoestrogen treatment studies in middle-aged women have shown time-limited positive effects on cognition function, and optimal phytoestrogen levels were associated with optimal memory functions in women of this age group in our Indonesian cohort. Effects of phytoestrogens on cognition may thus be modified by phytoestrogen levels obtained and age. These findings reflect those of estrogen treatment, where negative effects are found on cognition in older women and protective effects on cognition may occur in middle-aged women. Future studies should validate these findings and investigate potential mechanisms conferring risk and potential protective effects of phytoestrogens on the aging brain.