The first genetic study to exam the link between alcohol intake and telomere length – a marker of longevity – is worth paying attention to.
The scientists found that imbibing alcohol up to a certain amount each week won’t knock years off your life. But drink beyond this level and it will.
Are you within the limit?
You may recall that telomeres are regions of repetitive DNA sequences that cap chromosomes. They naturally shorten with aging, but more than normal shrinkage is tied to many age-related diseases, including heart disease, cancer, and Alzheimer’s disease.
Although genetic factors partly account for an individual’s telomere length, environmental and lifestyle factors such as a good diet, regular exercise and not smoking, play a big role in helping to keep them long, which in turn is linked to a longer life expectancy.
Up until now population studies that observe how alcohol consumption impacts telomere length have produced conflicting results. For example, researchers used different methods to measure telomeres and they categorized alcohol intake in different ways. Since multiple factors impact telomere length it hasn’t been possible to point the finger at alcohol’s negative impact on longevity with any degree of certainty.
To provide a more rigorous analysis, a research group led by Oxford University carried out not only an observational study but also the first genetic study. If you drink alcohol, their findings are worth paying attention to.
Ten drinks a week is the “longevity limit”
For their analysis the Oxford team used the UK Biobank which holds wide ranging medical, lifestyle, demographic, and genetic information on half a million people. Of these, researchers included 245,354 participants aged 40 to 69.
In the observational analysis, high alcohol intake was significantly linked to shorter telomeres. Compared with drinking less than two large 250ml (8½ fl oz) glasses of wine per week, drinking more than about ten glasses per week was associated with a one-to-two year age-related shortening in telomere length.
Participants diagnosed with alcoholism, or another alcohol-use disorder, had significantly shorter telomeres when compared with controls, equivalent to between three and six years of age-related change.
For the genetic analysis, researchers used a method called Mendelian Randomization (MR). This looked at genetic variants already linked to a particular behavior, in this case drinking alcohol. The advantage of using MR is that since genes are randomly allocated and fixed before birth, they’re less likely to be affected by lifestyle and other factors that make it difficult to interpret observational studies.
The researchers took the DNA samples from the UK Biobank and then screened them for 93 variants linked to increased alcohol use and 24 other variants linked to a diagnosis of alcohol use disorder. Their results showed higher genetically predicted alcohol consumption was associated with shorter telomere length.
However, this was only significant for those drinking just short of either six large glasses or ten five-ounce glasses of wine, ten regular beers or ten shots of spirit per week. Beyond this, telomeres get damaged, and we age faster. The analysis also found a significant association between genetically predicted alcohol use disorder and telomere length, equivalent to around three years of aging.
The reason is oxidative stress
Although this study doesn’t conclusively prove excess drinking shortens telomeres and accelerates aging, the researchers believe their analysis strongly supports this conclusion.
They suggest that the negative impact of alcohol on telomere length is via oxidative stress – excessive free radicals in cells – and inflammation.
Study leader Dr Anya Topiwala explained, saying, “These findings support the suggestion that alcohol, particularly at excessive levels, directly affects telomere length. Shortened telomeres have been proposed as risk factors which may cause a number of severe age-related diseases, such as Alzheimer’s disease.
“Our results provide another piece of information for clinicians and patients seeking to reduce the harmful effects of excess alcohol. Furthermore, the dose of alcohol is important – even reducing drinking could have benefits.”