Unlocking the Long-Term Effects of Smoking on Health: New Research Reveals the Benefits of Quitting

2024-02-23 19:58:23
According to two recent scientific publications, life expectancy almost returns to the level of non-smokers following ten years of abstinence. However, disturbances in the immune system may persist several years following stopping.

The impact of cigarettes on health continues to be the subject of fruitful research. A study published in the journal NEJM February 8 estimates that the probability of reaching the age of 80 is approximately the same for non-smokers as for those who stopped before turning 40. Enough to give balm to the heart of those for whom smoking was a temporary error of youth. Those who continue lose a dozen years of life compared to non-smokers.

“The key message is that quitting smoking is effective and rapid, and that it is beneficial to quit at any age,” insists the author of the study, Prabhat Jha, an epidemiologist in Toronto, to Libération. “At any age and compared to smokers, quitting smoking for less than three years can prevent the loss of five years of life. Quitting for more than ten years makes it possible to avoid ten years of lost life, which gives survival similar to that of people who have never smoked,” insist the researchers.

The very solid study is based on monitoring data from 1.48 million adults in four different countries (Canada, United Kingdom, United States, Norway). In this population, they compared the mortality risk by comparing active smokers, non-smokers and former smokers for less than three years, for three to nine years and for more than ten years. Not surprisingly, smokers are at greater risk of respiratory, vascular diseases and cancer.

If Prabhat Jha’s study only focuses on mortality, this is not the only effect of cigarettes. “Smoking modifies adaptive immunity in a persistent manner,” concludes another study published Wednesday February 14 in the journal Nature. This work highlights an element hitherto ignored: adaptive immunity, which is built over time with infections, remains damaged for years following stopping smoking.

These conclusions are based on a sample of one thousand people. These were selected more than ten years ago, as part of a project led by the Pasteur Institute in Paris, and their immunity was then regularly studied via various tests, particularly blood tests. This type of cohort monitoring allows us to assess how different factors influence health and metabolism over time. In the present case, it is smoking which stands out for its influence, more than other factors such as sleep time or the degree of physical activity, according to researchers led by biologist Violaine Saint-André.

“Preserve your long-term immunity”

We already knew that smoking harms the proper functioning of the immune system. The study confirms this, finding that part of this effect disappears immediately following stopping smoking. But, and this is the great novelty, it is not the same for the weakening of adaptive immunity.

This remains, in certain individuals, affected for years, even decades, following stopping smoking, even if the sample is too small and the reactions too variable to put forward a precise average duration. “To preserve your long-term immunity, it is surely better never to start smoking,” summarized biologist Violaine Saint-André at a press conference.

If knowledge is becoming more refined regarding the effects of smoking on the body, the public health messages remain the same: the best thing is not to smoke, or to stop as quickly as possible. Smoking kills some eight million people a year worldwide, according to the World Health Organization.

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