Out of time: Genetic evidence reveals smokers are literally shortening their lives

MILAN, Italy — Put down that pack of cigarettes if you want to stay youthful. An international team of scientists finds that smoking speeds up the aging process by shortening the chromosome ends of DNA.

A study involving nearly 500,000 participants shows that smoking reduces the length of DNA end fragments, called telomeres, in our immune system’s white blood cells. Shorter telomeres are associated with quicker aging and reduced cell repair capabilities.

“Our study shows that smoking status and cigarette quantity can result in the shortening of leucocyte telomere length, which is an indicator of tissue self-repair, regeneration and aging,” says Dr. Siyu Dai, an assistant professor in the School of Clinical Medicine at Hangzhou Normal University, in a media release. “In other words, smoking can accelerate the process of aging, while quitting may considerably decrease the related risk.”

Telomeres can be compared to the protective caps found at the ends of shoelaces. They protect the ends of chromosomes. Each time a cell divides, its telomeres shorten. Eventually, when they become too short, the cell can no longer divide and ultimately dies, which contributes to the aging process.

Longer genes could be the secret to the fountain of youth
Photo by Sangharsh Lohakare on Unsplash

Previously, smoking had been linked to shorter telomeres in white blood cells (known as leucocytes). However, there hadn’t been substantial research into the causal relationship between smoking, the number of cigarettes consumed, and telomere length.

For the study, scientists used data from the United Kingdom Biobank, examining the relationship between smoking habits and telomere length. They employed Mendelian randomization, a technique that uses genetic variations inherited from parents to determine the causal relationship between a modifiable factor (like smoking) and a health condition. This method helps eliminate potential bias from other unidentified factors.

The findings from the data of 472,174 UK Biobank participants demonstrated a clear link between current smoking status and reduced telomere length. Those who smoked more cigarettes exhibited a stronger shortening effect on their telomeres.

“In recent years, observational studies have linked shortened leucocyte telomere length with many diseases, such as cardiovascular disease, diabetes and muscle loss,” notes Dr. Dai. “This means that the effect of smoking on telomere length probably plays a critical role in these diseases, although more research is needed to understand the underlying mechanisms.”

Scientists will be conducting more research to confirm these findings and plan to delve deeper into the effects of second-hand smoke exposure on tissue aging, especially concerning children.

The findings are presented to the European Respiratory Society International Congress.

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  1. These studies typically address cigarettes, which are inhaled. It would be nice if they included cigars and pipes in these studies, which are not inhaled and differentiate the effects.

    1. There has been a lot of research about tobacco products that are not normally inhaled, like cigars, pipes, and snuff. The finds indicate that pipe and cigar smokers actually ‘inhale’ about as much as cigarette smokers do since their breathing air saturated with the smoke. Lung cancer studies confirm this with pipe and cigar smokers having similar heart and lung problems as cigarette smokers. Interestingly, pipe smokers and those who chew tobacco also have significantly higher mouth cancers than cigarette smokers

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