The findings, published in the March 2016 issue of the Journal of Studies on Alcohol and Drugs, may sound surprising after years of news stories tying moderate drinking to a range of health benefits, including a lower heart disease risk and longer life.
But the new analysis took a deeper look at those studies – 87 in all – and found that many were flawed, with designs suggesting benefits where there were likely none.
Professor Tanya Chikritzhs, head of the alcohol policy research program at the National Drug Research Institute, Curtin University, said the definition of abstainers had been a key issue.
Most often, studies had compared moderate drinkers – those who had up to two drinks per day – with current abstainers. The problem is that non-drinkers can include people in poor health who have cut out alcohol.
“A key question is, then, who are these moderate drinkers being compared against?” Dr Chikritzhs said.
When the research team corrected for those abstainer biases and certain other study-design issues, moderate drinkers no longer showed a longevity advantage.
Only 13 of the 87 studies avoided biasing the abstainer comparison group and these showed no health benefits.
Dr Chikritzhs said before those corrections were made, it was actually occasional drinkers—people who had less than one drink per week—who lived the longest, and it was unlikely that such infrequent drinking would be the reason for their better health.
“Those people would be getting a biologically insignificant dose of alcohol,” she said.
In addition, she noted, studies have linked moderate drinking to an implausibly wide range of health benefits.
The study did not look at whether certain types of alcohol, such as red wine, are tied to longer life, but if that were the case, Dr Chikritzhs said it would be unlikely that the alcohol content itself deserved the credit.
“There’s a general idea out there that alcohol is good for us, because that’s what you hear reported all the time,” she said.
“But there are many reasons to be sceptical.”