The study, based on 500,000 people, used techniques based on genetics to dispel existing wisdom that claimed drinking one or two alcoholic beverages a day could have protective properties.
Richard Peto, one of the study’s authors, concluded at the time that: “Claims that wine and beer have magical protective effects [are] not borne out.”
Now, a new paper which is set to be published in the International Journal of Epidemiology, argues that the 2019 study is “potentially unsound”.
Professor Sir Nicholas Wald of University College London, and Chris Frost of the London School of Hygiene and Tropical Medicine write: “We conclude that the observation in many studies that light drinking reduces the risk of stroke but heavier drinking increases it, is not necessarily disproved by the genetic analysis of Millwood and colleagues.
“It is important for public health policy that the true relationship between alcohol consumption and vascular disease is recognized.”
Previous epidemiological studies have shown a so-called J-shaped relationship between alcohol and stroke risk, in which people with low intake appear to have a lower risk than non-drinkers. This risk rises as drinking becomes heavier. When those risks are plotted on to a graph, the curve takes the shape of the letter J.
Frost and Wald show that the J-shaped relationship is not disproved by applying the genetic epidemiological analysis used in the 2019 paper.
“One cannot now say any amount of alcohol is harmful in the same way as one can say any amount of smoking is harmful,” Prof Wald told The Times.
He added that “the occasional glass of wine, or no more than a glass of beer, say, every other day would be acceptable given our current state of knowledge.
“One need not feel that the only safe alcohol intake is zero,” he said.
In June, a team of researchers at Imperial University London found that drinking any amount of alcohol, even within government guidelines, has a toxic effect on our organs, however.
The study, which examined MRI scans of approximately 10,000 people aged between 40-69 years to investigate whether there was a “safe level” of alcohol consumption, but concluded this was not the case.
“Our results imply that there is not a ‘safe threshold’ below which there are no toxic effects of alcohol,” the study’s authors said, adding that current public health guidelines “may need to be revisited”.
According to the NHS, both men and women are advised to drink no more than 14 units of alcohol per week.
A large glass of 12 per cent wine is equivalent to three units, as is a pint of high strength (5.2 per cent) lager or beer.
NHS guidance recommends that those regularly drinking this amount per week should try and spread their drinking over three or more days.
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