According to scientists at the University of Oxford, the answer to the age-old question of “how many drinks is really too much” is more than five large glasses of wine.
In the short term, a handful of pints of beer in the evening is known to make you feel the next day, but scientists have never before looked at how alcohol affects our aging process in the long term.
Oxford academics have now found that the limit is 17 units, or roughly five large glasses of wine or five pints of lager a week.
Any more than that and it starts to take its toll on our DNA, affecting the caps at the end of our chromosomes called telomeres.
Damage to these areas has previously been linked to Alzheimer’s and cardiovascular disease. People with healthier and longer telomeres are also thought to have longer lifespans.
Data from almost half a million people registered with the UK Biobank were used. The team looked for telltale genetic markers that show how much alcohol a person drinks. The length of their telomeres was measured in a laboratory after taking DNA from a swab.
Scientists found that a small amount of alcohol does not affect our DNA, but beyond the threshold of 17 units this changes and our telomeres are attacked.
The top 40% of drinkers, who consumed more than 17 units of alcohol per week, were found to have alcohol-induced telomere shrinkage.
However, the remaining 60% of people, who drank less than 17 units a week, were found to be genetically undamaged.
Someone who drinks 32 units a week, or about 10 large glasses of 13 percent ABV wine, is biologically three years older than someone who drinks ten units a week (about three large glasses of wine), for example.
“Minimum Quantity Required”
But the research found no link between alcohol consumption and biological aging below the 17-unit threshold, with someone who drank a glass of whiskey a week as unaffected as someone who drank a glass of wine every week
“This finding suggests that a minimal amount of alcohol consumption is required to damage telomeres,” the researchers write in their study, published in Molecular Psychiatry.
“Similar relationships with alcohol have been described for other health outcomes,” they add.
Exactly how alcohol intake relates to telomere damage is unknown, and this study does not provide causal evidence, but it does provide a strong observational connection.
A suggested potentially harmful mechanism is that the breakdown of alcohol molecules leads to oxidative stress and inflammation that are dangerous to DNA.
“These findings support the suggestion that alcohol, particularly at excessive levels, directly affects telomere length,” said study leader Anya Topiwala of Oxford Population Health.
“Shortened telomeres have been proposed as risk factors that can cause several serious age-related diseases, such as Alzheimer’s disease.
“Our results provide further information for clinicians and patients seeking to reduce the harmful effects of excess alcohol. Also, the dose of alcohol is important, even reducing alcohol consumption could have benefits “.
“Clear links with aging”
Dr Richard Piper, chief executive of Alcohol Change UK, welcomed the results.
He said: “This particular study shows clear links between alcohol consumption and ageing, and points towards a possible link between alcohol and Alzheimer’s.
“The researchers are transparent that this study does not demonstrate a causal link, but they also make a well-argued case for the likely biological mechanism.
“Overall, there is a growing body of science showing how exactly alcohol causes so much disease and so many early deaths.”
The NHS recommends that people drink no more than 14 units a week and that it should be spread over at least three days to avoid binge eating.