Evidence suggests that consumption of red wine reduces the risk of a number of diseases, particularly cardiovascular disease. This may relate in part to the presence of the alcohol within red wine, consumption of which has been shown to reduce the risk of myocardial infarction in the subsequent 24 hour period. However, alcohol cannot explain all the effects of red wine, as a number of physiological effects seen following consumption of red wine, are not seen with ingestions of ethanol (alcohol). Researchers have therefore investigated the other components of red wine that may confer cardioprotective benefits, and in this regard the polyphenolic content of wine has been identified for its health effects. These polyphenols are present in grapes and belong to the flavonoid class. Flavonoids give grapes their dark colour and so are present in particularly high concentrations in black grapes. Consumption of other products made with black grapes may also confer similar health effects.
A number of studies have investigated the cardioprotective effects of consuming grape juice. For example, in one study1, researchers compared the effects of grape juice, grapefruit juice and orange juice on platelet aggregation in healthy human subjects. Subjects consumed 6 to 7.5 mL per kg of body weight per day of one of the juices for 7 to 10 days, with each subject consuming all of the juices in a sequentially random orders. The results of the study showed that platelet aggregation was reduced with grape juice significantly from baseline (-77 %), whereas platelet aggregation in the orange and grapefruit juice groups showed no significant changes. Chemical analysis of the juices showed that the grape juice contained three times the total polyphenolic concentration of the citrus juices. Therefore these results support other findings that show that the beneficial platelet aggregatory effects of grapes may explain the ability of both red wine and grape juice to reduce the risk of cardiovascular disease.
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