Many studies of alcohol consumption benefits flawed, university director says

A new study has poured cold water on the idea that moderate alcohol consumption is healthy.

Many people enjoy a glass of wine with dinner happily believing that they are reducing the risk of heart disease and helping themselves to live longer.

But now researchers have re-assessed the science behind the claimed benefits of drinking within reasonable limits - and concluded that it is flawed.

Many of the 87 studies analysed were found to be poorly designed and biased, suggesting a positive effect when it was likely none existed.

A key issue was the way authors defined "abstainers" who provided the vital comparisons from which conclusions about the health effects of alcohol could be made.

Often, studies compared "moderate" drinkers who consumed up to two drinks per day with "current" abstainers. However, the abstainer group could include people who had cut out alcohol because they of poor health, it was claimed.

"A fundamental question is, who are these moderate drinkers being compared against?" said Dr Tim Stockwell, director of the University of Victoria's Centre for Addictions Research in British Columbia, Canada.

When Dr Stockwell's team corrected for abstainer biases and other alleged study design issues, moderate drinkers no longer showed a longevity advantage.

Only 13 of the 87 studies avoided biasing the abstainer comparison group, and none of these showed any health benefit associated with moderate alcohol consumption.

Before the corrections were made, it was actually "occasional" drinkers - people having fewer than one drink per week - who lived the longest, said Dr Stockwell. He doubts that such infrequent drinking could be the reason for their longer life spans.

"Those people would be getting a biologically insignificant dose of alcohol," he maintained.

The new research, published in the Journal of Studies on Alcohol and Drugs, did not look at whether certain types of drink, such as red wine, were linked to longer life.

If that proved to be true, alcohol itself would probably not deserve to take the credit, said Dr Stockwell.

He added: "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 sceptical."