(HuffPost) - Anyone who’s still drinking alcohol “for their health” should listen up.

Past research has shown that the chemicals in red wine may help fight aging and lower risk for cardiovascular disease and cancer. And indeed, research shows that moderate alcohol drinkers have longer lives than people who abstain. There’s just one problem with this conclusion: These studies often make the crucial mistake of including participants who abstain from alcohol for reasons that should exclude them. 

Now, a new review of 87 previous studies reveals that controlling for the right demographic factors contradicts findings that alcohol consumption is linked to a longer life. These studies, which included data from about four million people and 370,000 deaths, all showed that moderate, “low-volume” drinkers (one to two drinks a day) were less likely to die than people who abstained from alcohol. But that doesn’t mean moderate drinking led to longer life, and this new review suggests that it doesn’t. 

Here’s what ‘abstaining’ really means

Many people who fully abstain from alcohol do so because of medical conditions. They may quit drinking due to a medical condition or health consideration. Either way, these factors bias the “abstainer” group toward worse health than the general population that produces the “moderate” group.

“Giving up drinking is a sign of ill health, not a cause of it,” said Tim Stockwell, a psychology professor at the University of Victoria in Canada and the director of the Center for Addictions Research of BC. “So if those people are put in the abstainer comparison group, they make that group look unhealthy and make the moderate drinkers look healthier by comparison.”

A more precise way to compare the effects of alcohol on health would be to compare moderate drinkers to those who have abstained their whole lives, rather than include former drinkers, argued Stockwell.

Other factors that affect the quality of a study include controls for smoking status, age and ethnicity — something that low-quality studies did not do.