Adults who were exposed to tobacco during their fetal stage, in their mother’s womb, age more quickly. So do, even at a higher rate, those who started smoking as children and adolescents. Your biological age – the state of your cells, tissues and organs – is older than your chronological age, according to a study by Chinese researchers of more than 275,000 British people.
The work, published this Friday in the journal Science Advances, demonstrates how the environmental conditions of the first stages of life affect our long-term development, a hypothesis that was proposed in 2005. People who smoke have a greater risk of developing medical conditions. associated with age, such as chronic lung and cardiovascular diseases, type 2 diabetes, cancers and mortality in general. The research proposes that biological aging may be an explanation for this.
“The study highlights the importance of reducing tobacco exposure from the fetal period and during childhood, adolescence and adulthood, to promote longevity and prevent age-related diseases,” the authors write in their article. In Spain, approximately 20% of pregnant women smoke at some point during pregnancy, and more than 75,000 children between 10 and 14 years old do so daily.
Biological age can be measured from patients’ blood samples. There is no single way to estimate it, but there are various methods, each of which measures different indicators. The researchers have applied three of these methods to blood samples from 276,259 people who are part of the British biobank, a very extensive database that allows us to assess how genetics and lifestyle affect our health.
The magnitude of the effect differs between the methods, which estimate slightly different things—one measures how well the body is functioning, while another predicts the risk of death, for example—but the trend always coincides. Early contact with tobacco accelerates aging, and the effect is greater the earlier it starts and the longer it lasts.
Thus, indirect exposure in the fetal stage causes the body of an adult to have aged, on average, between a quarter and half a year more than what would correspond to its age, depending on the analysis method. Having smoked during childhood, on the other hand, increases the biological age of the adult between one and two and a half years, magnitudes that are greater the earlier consumption begins. When both situations occur, aging accelerates between one and three years.
The increase in biological age is not exclusively due to the fact of having had early contact with tobacco, but the habit acquired thereafter also plays a role. Those who start smoking as children tend to do so more as adults, and consume more cigarettes throughout their lives. The nature of the study does not allow us to determine how much each party contributes; it only points to early onset as a risk factor.
The quality of the database, however, includes a multitude of variables on lifestyle, health status, genetics and socioeconomic conditions. This has allowed researchers to rule out that the acceleration of aging could be due to these factors, which, however, can act as aggravating factors. Biological age increases to a greater extent in genetically predisposed people, and in those men of low socioeconomic status who follow unhealthy diets.
The research has also revealed that biological aging is more intense in participants under 50 years of age than in those over 60, something that previous research had suggested. The authors suggest that this may be due to the fact that some of those who have been exposed to tobacco in childhood have died, and that the people who survive have genetic and physiological factors that allow them to respond better to tobacco exposure.
The work is the most complete to date in the field, but despite having more than 250,000 participants, it does not yield definitive results, among other things because smoking habits were collected through surveys. Furthermore, the population analyzed is exclusively British, mostly white and with good socioeconomic and health conditions, so the results are not generalizable to the entire population.
Despite these unknowns, which also include the biological mechanism that can explain this aging, the article adds new evidence to the risk posed by tobacco consumption, especially when starting at a young age.
