Some researchers are questioning whether drinking moderate alcohol really helps people live longer (see this article
in the NY Times). Here's the main buzz: the link between living longer and drinking alcohol is an association. That means that there is, indeed, a link between people who drink moderately and people who live longer than average. The problem is that an association doesn't prove what is happening. It could be that people who drink a moderate amount of alcohol also do other behaviors that matter (such as exercising more or eating better foods). In the past, researchers have tried to control for these factors using surveys, but it is being questioned whether the surveys and other methods have really ruled out all the other factors that may make moderate drinkers healthier.
In the meantime, what seems pretty certain is that moderate alcohol consumption is not unhealthy and that it might even be healthy - so if you like to drink a bit, there is no reason not to (from a strict health perspective).
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