Dietary supplementation with fruit or vegetable extracts can ameliorate age-related declines in measures of learning, memory, motor performance, and neuronal signal transduction in a rat model. To date, blueberries have proved most effective at improving measures of motor performance, spatial learning and memory, and neuronal functioning in old rats. In an effort to further characterize the bioactive properties of fruits rich in color and correspondingly high in anthocyanins and other polyphenolics, 19-month-old male Fischer rats were fed a well-balanced control diet, or the diet supplemented with 2% extract from either blueberry, cranberry, blackcurrant, or Boysenberry fruit for eight weeks before testing began. The blackcurrant and cranberry diets enhanced neuronal signal transduction as measured by striatal dopamine release, while the blueberry and cranberry diets were effective in ameliorating deficits in motor performance and hippocampal HSP70 neuroprotection; these changes in HSP70 were positively correlated with performance on the inclined screen. It appears that the polyphenols in blueberries and cranberries have the ability to improve muscle tone, strength and balance in aging rats, whereas polyphenols in blueberries, cranberries and blackcurrants have the ability to enhance neuronal functioning and restore the brain’s ability to generate a neuroprotective response to stress.
