Exceeding weekly alcohol recommendations linked to short chromosomes

Regions of repetitive DNA sequence called telomeres cap our chromosomes, with shorter telomeres being linked to Alzheimer’s disease, cancer and heart disease

Source: https://www.newscientist.com/

August 8, 2022

Consuming 17 or more units of alcohol a week, just beyond the UK’s recommended upper limit, has been linked with shortened telomeres.

Telomeres are regions of repetitive DNA sequence that cap chromosomes, like the plastic tip on the end of shoelaces. “Telomere length decreases as we age in normal ageing, but the concern is that shorter telomeres have been linked with lots of diseases of later life like cancer, Alzheimer’s disease and heart disease,” says Anya Topiwala at the University of Oxford.

To better understand alcohol’s effect on telomere length, Topiwala and her colleagues analysed 245,354 participants – aged 40 to 69 – of the UK Biobank study, which holds medical and genetic information on half a million people.

Telomere length was calculated from a single blood sample taken from each participant. The team compared this with the participants’ self-reported weekly alcohol consumption.

Results reveal the participants who had been diagnosed with alcohol-use disorder were more likely to have shorter telomeres. A statistical analysis suggested this wasn’t a chance finding.

But this type of comparison can’t tell the researchers whether alcohol alone is at least partly responsible for shorter telomeres, as other lifestyle factors like diet may also influence telomere length.

To better understand the role of alcohol specifically, the researchers repeated the experiment, this time using data from an earlier genome-wide association study (GWAS) that found 93 genetic variants associated with increased alcohol use.

“It’s sort of like a randomised control trial,” says Topiwala. “Like when you randomise people to have a drug or not have a drug, but obviously you can’t do that with alcohol.”

This method, called mendelian randomisation, groups people by the genetic variants they possess that have been linked to particular behaviours. The idea is these genes were randomly allocated at conception and are therefore not affected by lifestyle factors.

The team devised a genetic risk score based on these variants and found that the participants with a higher genetic risk score for increased alcohol consumption were more likely to have shorter telomeres.

In both the Biobank and GWAS experiments, the team found that the participants who had been diagnosed with alcohol use disorder had the shortest telomeres. But shorter telomeres were also seen in those who were genetically more likely to consume between 17 and 28 units a week.

The UK’s National Health Service recommends both men and women don’t regularly exceed 14 units of alcohol a week, the equivalent to six pints of average-strength beer or 10 small glasses of lower-strength wine. According to NHS data, 57 per cent of adults in the UK consumed less than this a week in 2019.

In the US, men are advised to have no more than two alcoholic drinks a day, falling to one drink for women.

Regular alcohol consumption can increase oxidative stress – caused by a build-up of damaging free radicals in cells – and inflammation, which leads to shortened telomeres, according to Topiwala.

Overall, the study provides more evidence for the notion that even 17 units of alcohol a week can be harmful to health, she says.

Carmen Martin-Ruiz at Newcastle University in the UK says the fact that telomere length was only calculated once per person means the study can’t definitively say whether telomeres shorten due to regular alcohol consumption. “They did not measure the telomeres of people at different time points,” she says.