Thinking about a glass of wine a day for a longer life? Well, the long-held notion that moderate alcohol consumption boosts longevity may be misleading, as researchers have found that no amount of alcohol is truly safe for health benefits.
Many studies have suggested that moderate drinkers enjoy longer lives and reduced risks of heart disease and other chronic conditions compared to abstainers. However, a new report published in the Journal of Studies on Alcohol and Drugs that analyzed 107 studies on drinking and lifespan revealed that such studies often suffer from underlying design flaws.
The researchers point out that the problem with earlier studies is that they often centered on older adults without accounting for their lifetime drinking patterns. This means that moderate drinkers were compared against "abstainers" and "occasional drinkers," but these groups included older adults who had reduced or stopped drinking due to health problems.
"That makes people who continue to drink look much healthier by comparison," lead researcher Tim Stockwell, a scientist with the Canadian Institute for Substance Use Research at the University of Victoria, said in a news release.
Initially, when researchers pooled the data from all the studies, it seemed that light to moderate drinkers who consume between one drink per week and two per day had a 14% lower risk of dying compared to abstainers.
However, a deeper analysis revealed that in "higher-quality" studies focusing on younger participants (under 55, on average) and excluding former and occasional drinkers from the abstainer group, moderate drinking showed no clear link to a longer life.
"If you look at the weakest studies, that's where you see health benefits," Stockwell said. The lower-quality studies typically involved older participants and showed no distinction between former drinkers and lifelong abstainers.
"Studies with life-time selection biases may create misleading positive health associations. These biases pervade the field of alcohol epidemiology and can confuse communications about health risks. Future research should investigate whether smoking status mediates, moderates, or confounds alcohol-mortality risk relationships," the researchers concluded.
"In reality, moderate drinking likely does not extend people's lives--and, in fact, carries some potential health hazards, including increased risks of certain cancers. That's why no major health organization has ever established a risk-free level of alcohol consumption. There is simply no completely 'safe' level of drinking," Stockwell said.
