Oxidative stress protection and vulnerability in aging: putative nutritional implications for intervention.

Research indicates that vulnerability to oxidative stress (OSV) may increase in aging, suggesting that age-related neurodegenerative diseases such as Alzheimer's disease (AD) or vascular dementia (VAD) may be superimposed upon a vulnerable neuronal environment. Determinations in cell models have suggested that the enhanced OSV may be the result of, (a) increases in membrane lipids, especially sphingomyelin and the sphingomyelin metabolite, sphingosine-1-phosphate, (b) decreases in glutathione, and (c) CNS distribution of OS-sensitive neuronal muscarinic receptor subtypes (e.g. M1, M2 and M4). These changes appear to enhance, (a) decrements in cellular calcium buffering following KCl-induced depolarization, and (b) cell death under OS conditions. Among the most effective agents that antagonized cellular OSV were the combination of polyphenolics found in fruits (e.g. blueberry extract) with high antioxidant activity. Subsequent experiments using dietary supplementation with fruit (strawberry) or vegetable (spinach) extracts have shown that such extracts are also effective in forestalling and reversing the deleterious effects of behavioral aging in F344 rats. Thus, it appears that the beneficial effects of the polyphenolics found in fruits and vegetables in neuronal aging and behavior may be similar to those seen with respect to carcinogenesis and cardiovascular disease.