In yet another study that confirms researchers’ understanding of how alcohol impacts the human body and its general health, investigators found that moderate drinking has a mild effect on decreasing likelihood of death (mortality). According to the study, which appeared in the Dec. 11 2006 issue of Archives of Internal Medicine, drinking a moderate amount of alcohol — 3 to 4 drinks per day in men and 1 to 2 drinks per day in women — reduces the risk of death from any cause by 16 to 18 percent. (Abstract here.)

The study was a meta-analysis conducted by an Italian group of researchers. The investigators searched PubMed for articles available until December 2005, supplemented by references from the selected articles. Thirty-four studies on men and women, for a total of 1,015,835 subjects and 94,533 deaths, were analyzed. A meta-analysis study looks at all of the data from a number of studies and using advanced statistical methods, can draw reliable conclusions about the data across all the studies. Often the key to whether a meta-analysis is valid or not is the inclusion/exclusion criteria it uses to include studies in its examination.

The study authors note that their “findings, while confirming the hazards of excess drinking, indicate potential windows of alcohol intake that may confer a net beneficial effect of moderate drinking, at least in terms of [overall, long-term] survival.”

The reason why men are protected at up to four drinks per day, while women lose the protection after two glasses has to do with how men and women metabolize alcohol, the researchers said. It’s been shown that when men and women who drink the same amount of alcohol, women experience higher blood alcohol levels than men.

Men who have more than four drinks per day and women who have more than two drinks per day not only lose the protection that alcohol affords, but they increase their risk of death, the study concluded.