We've seen a few studies plug the benefits of modest alcohol consumption; the anti-oxidants in wine are one possible explanation. However, a study in an alcoholism journal found that heavy drinkers did better than non drinkers-
But even after controlling for nearly all imaginable variables — socioeconomic status, level of physical activity, number of close friends, quality of social support and so on — the researchers (a six-member team led by psychologist Charles Holahan of the University of Texas at Austin) found that over a 20-year period, mortality rates were highest for those who had never been drinkers, second-highest for heavy drinkers and lowest for moderate drinkers.
The study proper is behind a pay wall, so I don't know exactly what the control factors are. However, there is one breakdown that isn't mentioned, the fact that we can divide non-drinkers into two categories.
One is people who choose not to drink for social or religious reasons and the other is people who can't drink because of a medical condition. For instance, someone with juvenile-onset diabetes shouldn't have alcohol and may have never gotten around to developing a drinking habit. Or, people who are on antidepressants might be forced away from booze and may have done so from teen years on.
That second grouping of forced abstainers might be a bigger health risk and die sooner. If those people were factored out of the mix, then we'd have a clearer look at what non-drinking does.