Q: Does wine that has been opened lose its health benefits? That is, once exposed to air do wine’s health properties deteriorate so that the glass I have on night one is helpful but the wine I drink day two is less so? --Alan
A: Once wine has been opened, it is more susceptible to oxidation, a process that changes the chemical make-up of the wine. Ethanol alcohol is converted to acetaldehyde and then to acetic acid (a component of vinegar) and different phenolics, such as tannins, are altered. How quickly this happens depends on the age and type of the wine, so it's hard to generalize. Some wines, especially older ones, will change quickly, whereas younger, more tannic wines might actually benefit, at least taste-wise, from some aeration (Check out these tips on how to preserve wine once it has been opened). But is wine that has been exposed to air any more or less healthy? Hard to say. Scientists are still trying to pinpoint why drinking wine in moderation correlates with health benefits. Some speculate that the alcohol itself could be the key, while others are focusing their research on polyphenols like resveratrol or quercetin. As it stands, evidence suggests that health benefits arise from regular moderate drinking over the course of a lifetime, so your best bet is to choose wines that you like.
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