Studies are increasingly hailing the potential health benefits of moderate alcohol consumption, particularly when it comes to the heart and lifespan. But new research suggests many of these studies are flawed and that such benefits may be largely overestimated.

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The researchers say we should be skeptical of studies reporting the health benefits of moderate drinking.

Lead researcher Tim Stockwell, PhD, of the Centre for Addictions Research at the University of Victoria, Canada, and colleagues reached their conclusion by analyzing 87 studies that assessed the effects of moderate drinking on longevity.

They recently published their findings in the Journal of Studies on Alcohol and Drugs.

According to the National Institute on Alcohol Abuse and Alcoholism (NIAAA), over the past month, around 24.6% of adults report engaging in binge drinking and around 6.8% report engaging in heavy drinking.

Such drinking habits can increase the risk of alcohol use disorders, which affect around 16.6 million adults and 697,000 adolescents in the US.

On the other hand, numerous studies have suggested that, in moderation, alcohol may be good for us.

A recent study reported by Medical News Today, for example, suggested moderate drinking – defined in the study as three to five alcoholic beverages a week – may lower the risk of heart attack and heart failure.

However, the new research from Stockwell and colleagues suggests the results of such studies should not be taken at face value, after finding that many of them are subject to biases that, when accounted for, eliminate the reported health benefits of moderate drinking.

From analyzing 87 studies that looked at the effects of alcohol consumption on death from all causes, the team identified a number of flaws in the way the studies were designed.

One major issue they found was how the studies defined “abstainers” – people who do not drink alcohol.

The researchers explain that many of the studies compared moderate drinkers – which they define as individuals who consume up to two alcoholic beverages daily – with “current” abstainers, but these abstainers may include individuals of poor health who have stopped drinking.

“A fundamental question is, who are these moderate drinkers being compared against?,” says Stockwell.

In their analysis, the researchers found that only 13 of the studies they assessed avoided biases in the abstainer group, and these studies demonstrated no mortality benefits with moderate drinking.

Furthermore, when the researchers accounted for this bias and other flaws they identified related to study design, they found that moderate drinkers no longer showed any mortality benefits.

Additionally, the researchers found that it was “occasional” drinkers – defined as individuals who consume less than one alcoholic beverage a week – who had the longest lifespan, and the team says it is unlikely that alcohol is the reason for this.

“Those people would be getting a biologically insignificant dose of alcohol,” notes Stockwell.

The team points out that the research did not investigate how specific types of alcohol – such as red wine, largely hailed for its health benefits when consumed in moderation – was associated with longevity, but Stockwell says it is doubtful any health benefits would be down to the alcohol itself.

Overall, the team believes their results suggest studies hailing the health benefits of moderate drinking should be viewed with caution. Stockwell says:

There’s a general idea out there that alcohol is good for us, because that’s what you hear reported all the time. But there are many reasons to be skeptical.”

MNT recently reported on a study that suggested just the smell of alcohol can reduce levels of control over behavior.