Red wine is known to have important health benefits because of the phytonutrients it contains. While epidemiological studies suggest that red wine consumption is beneficial, it is still unclear as to which grape derived components provide the health benefits. Red wine is a complex mixture of polyphenols with the exact chemical composition varying depending on the growing conditions of the grapes and the manufacturing process of the wine. Resveratrol (3, 4’, 5-trihydroxystilbene) is a phytoalexin polyphenol that has been isolated from grapes which may impart some of the health benefits associated with red wine. Studies suggest that resveratrol may increase blood flow, modulate nitric oxide synthesis and promote the cellular redox state by regulating antioxidant enzymes through the Nfr2 transcription factor. Via these physiological changes resveratrol is known to increase cerebral blood flow and this may explain its ability to prevent neurodegeneration.
To investigate the effects of resveratrol on cognitive performance and cerebral blood flow, researchers1 fed two doses of oral resveratrol (250 and 500 mg) to 22 healthy subjects. After consuming the supplements, the subjects performed a series of tests that activated the frontal cortex. The researchers measured the cerebral blood flow by monitoring the concentration of oxygenated and deoxygenated haemoglobin using near infra-red spectroscopy. The results demonstrated that resveratrol resulted in a dose dependent increase in cerebral blood flow as measured by increases in total concentrations of haemoglobin. Increases in deoxyhaemoglobin suggested that resveratrol had caused an increase in oxygen extraction by the frontal cortex. However, cognitive function was not affected. Samples of blood were also taken from another group of subjects and these showed that resveratrol was present in plasma for the duration of the test period.
Despite the lack of improvement in cognitive performance, these results are interesting in that they suggest that resveratrol may be able to modulate cerebral blood flow. This may explain the epidemiological evidence that frequently red wine consumption is associated with a reduced incidence of strokes. Research also suggests that stroke victims can benefit from resveratrol supplementation because the improvement in blood flow to the brain may aid the repair process, by providing nutrients and facilitating removal of waste. The improved blood flow also appears to be protective of neurodegeneration, with moderate consumption of wine being associated with lower incidence of Alzheimer’s disease. Red wine is a good source of resveratrol and also contains other polyphenols which have possible health benefits. Grapes and grape juice also contain resveratrol, which is found mainly in the skin of the grape.
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