Smoking can speed up the ageing process in younger people by more than two decades, according to new research.
Men and women who use cigarettes are twice as old as non smokers – biologically, say scientists.
The human body has two different ages – known as chronological and biological.
The latter refers to how old a person seems – rather the actual time they have been alive.
Now, blood tests on 149,000 adults has found smokers were estimated to be two times as old as their chronological age, compared to non smokers, by middle-age.
More than seven in ten samples from smokers younger than 30 were predicted to be in the ranges of 31 to 40 years old – or 41 to 50.
On the other hand, the ages of most of the non-smokers (62%) were calculated accurately.
The same trend was found for 31 to 40 year olds, in which the ages of almost half (43%) of the smokers were predicted to be 41 to 50.
Study author Dr Polina Mamoshina said: “Compared with nonsmokers, smokers showed an accelerated rate of ageing through to age 55 years regardless of sex.”
Curiously, these differences then disappeared – and perhaps even reversed themselves for the most elderly subjects.
She explained: “In the context of biological ageing, this suggests the contribution of tobacco smoking as an external factor of ageing may eventually be masked by the intrinsically physiologically deleterious nature of the ageing process.
“Alternatively, the people most affected by smoking may have died at an earlier age and thus were be excluded from the old-age smoking group.”
The dangers of smoking are well known, increasing the risk of a host of conditions from cancer and cardiovascular disease to asthma and diabetes.
This is on top of making an individual appear older, narrowing the skin’s blood vessels causing it to sag and wrinkle.
But the study, the first of its kind, suggests the habit causes even more damage to the internal workings of the body than previously feared.
Around a third (49,000) of the participants were smokers, and their average age was 55.
Dr Mamoshina, a senior research scientist at Baltimore-based artificial intelligence solutions company Insilico Medicine, said: “Smoking is a real problem that destroys people’s health, causes premature deaths and is often the cause of many serious diseases.”
She said the findings published in Scientific Reports home in on exactly how much harm it causes.
Previous research has shown biological age is more useful than using a date of birth for predicting when a person will die.
In the UK there are about 9.4 million current smokers, and 38 million in the US.
It is the biggest cause of death and illness in Britain, claiming more than 120,000 lives each year through associated diseases.
This means it accounts for over a fifth of deaths, similar to the US where it is responsible for about 480,000 deaths annually.
Dr Mamoshina and colleagues combined an age-prediction model using a technique called deep learning and various biochemical markers among the participants.
These included levels of blood sugar, fasting glucose, iron stores and urea, a waste product excreted in urine.
Dr Mamoshina said: “The results showed smokers had a higher ageing ratio than people who didn’t smoke.”
Her team say the analysis of blood tests could soon replace traditional self reporting methods used to evaluate the effects on ageing of other lifestyle choices such as diet, exercise and alcohol consumption.
Insilico Medicine uses artificial intelligence, or computer learning, to research ageing and drug development to “extend healthy longevity.”
Dr Mamoshina said; “We applied artificial intelligence to prove that smoking significantly increases your biological age.”
The results were the same for both male and female smokers. She said smoking has long been proven to negatively affect people’s overall health in multiple ways.
So her team set out to determine biological age differences between smokers and non-smokers using blood biochemistry and recent advances in AI.
Added Dr Mamoshina: “I am pleased to be part of the research study, which provides fascinating scientific evidence that smoking is likely to accelerate ageing.”
By Ben Gelblum and Mark Waghorn