After quitting smoking, immunity is slow to recover and is actually more damaged than previously thought, AFP reported, citing two scientific studies on the long-term effects of tobacco on health. 

Smoking affects the adaptability of the immune system in a very persistent way, concludes a study published in the journal "Nature". 

According to the World Health Organization (WHO), eight million people die each year as a result of smoking. 

A non-smoking woman's face is printed on millions of cigarette packs in Europe without her knowledge

The research draws attention to a hitherto ignored aspect - adaptive immunity, which remains impaired years after smoking cessation. The conclusions are based on research done on a thousand people selected over more than ten years for a project of the Louis Pasteur Institute in Paris. The patients' immunity was regularly tested by various methods, mostly by blood, to see how individual factors affect health and metabolism. The most decisive factor appears to be smoking, followed by sleep duration and physical activity, says the study with lead author biologist Violen Saint-André. 

This is nothing new - smoking is known to affect innate immunity and worsen inflammatory responses. The current scientific study confirms this, finding that this effect disappears immediately after smoking cessation. The big news is that things are not the same for adaptive immunity. Regarding it, the effect remains in some patients, lasts for years, even decades. Scientists have gone even further, finding a connection between these problems of adaptive immunity and an epigenetic effect - the patients' DNA remains unchanged, but exposure to tobacco affects the way some genes actually function. 

This conclusion does not mean that there is no point in stopping smoking. Side effects gradually subside. But in order to maintain long-term immunity, it is better not to start at all, Saint-Andre emphasized during a press conference. 

This research, based on biological studies, cannot answer the question of what the health consequences of immune variation are. According to the authors, there should be consequences on the risk of infections, cancers, autoimmune diseases. However, this remains a hypothesis at this stage. 

Another study, published in NEJM Evidence, determined exactly how much health risks increase when you stop smoking. It took into account data from 1.5 million people in Canada, the US, Norway and the UK. The scientists compared the mortality rate between different groups: active smokers; people who have never smoked; former smokers. In the last group - that of ex-smokers, the risks gradually decrease over time. After they stopped smoking, patients needed ten years to catch up with the second group - those who had never smoked. 

And in relation to this research, the conclusion that stopping has no immediate benefits should be avoided - the benefits are visible three years later, the study says. Life is extended by an average of five years, which is halfway to the hope of a normal life. The effect of smoking cessation is most visible in people under 40 years of age. 

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