One of the most contentious issues in the vast literature about alcohol consumption has been the consistent finding that those who don't drink actually tend to die sooner than those who do. The standard Alcoholics Anonymous explanation for this finding is that many of those who show up as abstainers in such research are actually former hard-core drunks who had already incurred health problems associated with drinking.
But a new paper in the journal Alcoholism: Clinical and Experimental Research suggests that - for reasons that aren't entirely clear - abstaining from alcohol does actually tend to increase one's risk of dying even when you exclude former drinkers. The most shocking part? Abstainers' mortality rates are higher than those of heavy drinkers. (See pictures of booze under a microscope.)
Moderate drinking, which is defined as one to three drinks per day, is associated with the lowest mortality rates in alcohol studies. Moderate alcohol use (especially when the beverage of choice is red wine) is thought to improve heart health, circulation and sociability, which can be important because people who are isolated don't have as many family members and friends who can notice and help treat health problems.
But why would abstaining from alcohol lead to a shorter life? It's true that those who abstain from alcohol tend to be from lower socioeconomic classes, since drinking can be expensive. And people of lower socioeconomic status have more life stressors - job and child-care worries that might not only keep them from the bottle but also cause stress-related illnesses over long periods. (They also don't get the stress-reducing benefits of a drink or two after work.)
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. (Watch TIME's Video "Taste Test: Beer With Extra Buzz.")