The last cigarette
At some point, it is the last one. Maybe on an ordinary evening on the balcony, maybe after a doctor's appointment, maybe simply because enough is enough. The cigarette is stubbed out, the pack goes in the bin. From the outside, this moment looks unremarkable.
Inside the body, however, something remarkable begins. After just a few weeks, the first blood values recover, and with every smoke-free year the repair continues. The body starts to clear away damage that has built up over years.
This brings us right to biological age. Your chronological age counts the years since you were born. Your biological age describes the actual condition of your body, for example how much strain your cells and blood vessels are already under. Hardly any factor drives this biological age up as strongly as smoking. And hardly any can be turned back so clearly. One of the most famous studies in the history of medicine shows just how big this effect really is.
34,000 doctors, 50 years and a clear answer
In 1951, two British researchers, Richard Doll and Austin Bradford Hill, wrote to all the doctors in the country. They asked about something seemingly simple: do you smoke, and if so, how much? Back then, smoking was completely normal, including among doctors. Around 34,000 men replied, and the researchers followed them for the next 50 years.
The result, which Doll published together with his colleague Richard Peto in 2004, is as clear today as it was then: people who smoked all their lives lived on average about ten years less than people who had never smoked.
The second finding is at least as important. Those who quit won back a large share of those years. People who quit at 30 regained almost the full ten years. At 40 it was about nine, at 50 about six, and even at 60 still around three years.
It is never too late to quit. But every year earlier pays off.
Traces in the cells: Why smoking speeds up biological age so much
Where does this huge effect come from? Much of it can be explained by the lungs, heart and blood vessels. But smoking also leaves traces that run much deeper.
With every puff, thousands of chemical substances enter the body. Many of them irritate tissue, not only in the lungs but, via the blood, throughout the entire body. The immune system responds as if to an injury that never fully heals: it stays constantly on duty and keeps a mild, permanent inflammation going. You do not feel any of this, but the tissue has to repair itself again and again, and the cells have to divide more often to do so.
This is exactly where the telomeres come in, the protective caps at the ends of our chromosomes. With every cell division they get a little shorter. People who smoke therefore use up this protection faster. Accordingly, studies show that smokers have shorter telomeres on average, and the more they have smoked, the shorter they are. You can find out more about telomeres here (Article: Biological age).
So smoking does not stay in the lungs. It leaves its mark right down to individual cells.
What happens after you quit
The good news: the body recovers remarkably well. Some inflammation markers in the blood return to normal within just a few weeks. After about a year, the additional risk of heart disease has dropped considerably, and after around 15 years it is close to that of people who have never smoked.
To be honest, though, some traces remain. The risk of lung cancer, for example, drops considerably but does not quite reach the level of non-smokers even after many years. For everyone who used to smoke, this mainly means one thing: every smoke-free year counts, and a large part of the recovery carries on all by itself.
And what about smoking just a little? Many people think a few cigarettes a day are harmless. A large analysis of 141 studies shows otherwise: just one cigarette a day carries about a third to a half of the additional heart risk of 20 cigarettes. Cutting down is therefore a good first step, but the real goal remains quitting completely.
How to succeed in quitting
Quitting is hard, and that is not down to a lack of willpower. Nicotine is addictive, and smoking is often closely tied to everyday situations: the morning coffee, the break at work, the evening with friends. That is why many people need several attempts, and that is completely normal.
If you get support, your chances are much better. Proven options include counselling, for example by phone or in courses, and aids such as nicotine patches or medication, which you can discuss with your GP. It also helps to pick a fixed quit date and to plan ahead for your typical smoking situations.
For your biological age, the day you quit is one of the most valuable days of all.
Where you stand on smoking
How much you currently smoke and how much you have smoked in total are two of the questions in the BioAge test. Together with the other questions, they produce an estimate of your biological age and an overview of where you have the most to gain.
Frequently asked questions about smoking and biological age
Are e-cigarettes or heated tobacco products a good alternative?
According to current knowledge, they contain fewer harmful substances than tobacco smoke, but they are not harmless, and long-term data are still lacking. As an aid to quitting, they can be an intermediate step for some people, ideally with a clear plan. For your biological age, being completely smoke-free is the best choice.
Will I gain weight if I quit?
Many people put on a few kilos in the first year, about four to five on average. Even so, the health gain from quitting is many times greater. Regular exercise helps keep your weight in check. Read more here (Article: Endurance).
What helps with cravings in the first few weeks?
The acute urge to smoke usually lasts only a few minutes. Distraction, a glass of water, a short walk in the fresh air or a few deep breaths help you get through these moments. The strongest withdrawal symptoms usually ease considerably after a few weeks.
Is passive smoking harmful too?
Yes. Regularly breathing in other people's smoke also puts a strain on the heart, blood vessels and lungs. A smoke-free home and a smoke-free car therefore protect not only you, but also the people around you.