Submitted to: Nutritional Neuroscience
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/31/2000
Publication Date: 12/1/2000
Citation: Youdim, K.A., Shukitt-Hale, B., Martin, A., Wang, H., Denisova, N., Bickford, P.C., and Joseph, J.A. Short-term dietary supplementation of blueberry polyphenolics: Beneficial effects on aging brain performance and peripheral tissue function. Nutr. Neurosci. 2000, 3: 383-397. Interpretive Summary: One of the most profound changes of recent years has been the dramatic increase in the global population of aged people, consequently posing serious social issues. For example, neurodegenerative disorders such as Alzheimer's disease (AD) and Parkinsons' disease (PD), with their attendant motor and cognitive deficits, increase with aging. However, such himpairments in cognitive performance have also been shown to occur in the absence of these disorders. Common components thought to contribute to the manifestation of these disorders and normal age-related declines in brain performance are increased susceptibility to long-term effect of oxidative stress (OS) and inflammatory mediators. In order to best combat against or possibly delay the onset of neurological impairments, new interventions through accessible dietary sources are warranted. As such, if OS is involved in either manifesting or propagating the aforementioned deleterious changes in brain function, then these alterations should be prevented or retarded by antioxidants. One source identified by our laboratory are polyphenolics isolated from blueberries. Rats consuming diets containing these polyphenolics displayed improved memory and brain functions. In addition, tissues such as the liver also displayed signs of improved function. These observations are particularly striking as blueberry supplementation was superimposed on an already well-fortified diet, containing more than adequate amounts of antioxidants, suggesting an increased antioxidant potency promoted by these polyphenolics or protection through some other mechanism yet to be identified.
Technical Abstract: Emerging evidence from our lab indicates 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's disease. The current study examined if the beneficial effects were also discernible 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. Such effects may have been due to the observed increase in striatal vitamin C levels. Results from assessment of serum transaminase levels in BB supplemented animals suggest improved liver function; the liver is utilized by rats to synthesize vitamin C. Beneficial effects observed within the periphery also included a reduction in the free radical generation within red blood cells, together with changes in their membrane fluidity. 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.