Short-Term Dietary Supplementation of Blueberry Polyphenolics: Beneficial Effects on Aging Brain Performance and Peripheral Tissue Function

Emerging evidence from our lab indicate that fruits and vegetables, in particular blueberry (BB) extracts, are able to ameliorate age-related declines in neuronal and cognitive function, common in disorders such as Alzheimer disease. The current study examined if the beneficial effects were also discernable with supplementation of BB extracts, in an already well balanced diet. Indeed, following an 8 week supplementation regime, age-related declines in several behavioral parameters such as balance, coordination, working memory and reference memory were still protected against. Similarly, BB extracts also potentiated oxotremorine enhancement of K⁺-evoked release of dopamine from striatal slices. Decline in the dopaminergic system have been shown to have a profound effect on cognitive functions. The improvement in dopamine release may have been due in part to the observed increase in striatal vitamin C levels. Although assessment of serum transaminase levels in BB supplemented animals appeared to suggest improved liver function, this was not thought to be the reason for the elevated vitamin C levels. The underlying mechanism for this is unclear. Together these findings highlight the diverse in vivo actions of dietary polyphenolics, a number of which may be important against age-related declines in certain brain functions. Furthermore they are to be able to mediate protective effects despite the diet containing sufficient concentrations of antioxidants.