Stub it out: healthy lung cells can regrow after quitting smoking, new research finds


We all know that smoking is possibly the most damaging thing you can do to your lungs. It’s been directly linked to at least 15 different types of cancer and is responsible for around 70% of lung cancer cases in the UK - the most common cause of cancer death.

But did you know that some of the damage done to your lungs’ protective cells can be reversed?

New research has shown that the body can actually deck the airways with fresh, non-cancerous cells once you quit smoking - even if you were a heavy smoker.

A team from UCL and the Wellcome Sanger Institute has found that people who once smoked regularly had substantially more genetically healthy cells than those who still smoked.

Our bodies are full of cells which over time steadily mutate (up to 50 mutations a year). The vast majority of these mutations are totally harmless, but occasionally, certain genetic changes (known as ‘driver mutations’) can push a cell down the path towards cancer.

The more driver mutations you have, the more at risk of disease you are.

Scientists looked at the genomes of 632 cells from 16 middle-aged people - four of whom were never-smokers, six ex-smokers and three current smokers. They also analysed the cells of three children.

Although they found that mutations occurred with general aging in the never-smokers, only 5% of them had any dangerous mutations. For the current smokers, however, they found that each lung cell had 5,000 more mutations than non-smokers, with some cells having up to 15,000 mutations. And they also had a massive increase in driver mutations.

So far, so predictable.

But the really interesting finding was in the group of former smokers.

The scientists found that they fell into two groups: one had the thousands of extra mutations found in current smokers. But the other group seemed to be back to normal - with cells that looked similar to those of someone who had never smoked.

Their number of normal cells was four times larger than in current smokers, suggesting that the lungs have the ability to replenish the lining of the airways once you’ve quit. And that was evident even in people who had smoked a packet of cigarettes every day for over 40 years.

That discovery is exciting because we now know that given half a chance, our bodies can replenish and protect us from disease. The next port of call is to work out why some cells manage to avoid getting damaged and others don’t.

“People who have smoked heavily for 30, 40 or more years often say to me that it’s too late to stop smoking – the damage is already done,” said senior author Dr Peter Campbell from the Wellcome Sanger Institute in a statement.

“What is so exciting about our study is that it shows that it’s never too late to quit – some of the people in our study had smoked more than 15,000 packs of cigarettes over their life, but within a few years of quitting many of the cells lining their airways showed no evidence of damage from tobacco.”

Ditching the cigs will not only save you a tonne of cash and slow down the rate of further damage, but it can even reawaken cells that haven’t been damaged by the habit. It really is never too late to quit.

Tips for quitting

  • Nicotine replacement therapy: a review of 136 trials with 64,640 people found that all forms of NRT helped smokers to quit. In fact, the chances of kicking the habit for good increased by up to 60% - regardless of setting.
  • Get support: telling someone that you’re trying to quit can improve your chance of success. It’s the same kind of psychology that comes from joining slimming clubs - group support can be key. If you don’t have a non-smoking friend or family member who can help you stay accountable, why not try a free, local Stop Smoking group?
  • Keep it moving: smoking may be an addiction but it’s also a habit - so while you’re trying to quit, why not swap a bad habit for a good one? Upping your exercise is not only a great distraction but it’s also a good way of seeing how much your lung capacity improves as you go further along your smoke-free journey. A 20 minute jog might feel tough initially but after a few months of not smoking, you’ll notice a real difference.
  • Change your diet: a US study found that some foods and drinks (like meat, coffee and booze) can make a post-dinner cig even more satisfying. Others (like cheese, fruit and veg) can make cigarettes taste disgusting. So swap your steak and wine for a veggie pizza and juice.

Information contained in this Articles page has been written by talkhealth based on available medical evidence. The content however should never be considered a substitute for medical advice. You should always seek medical advice before changing your treatment routine. talkhealth does not endorse any specific products, brands or treatments.

Information written by the talkhealth team

Last revised: 13 February 2020
Next review: 13 February 2023