Smoking Can Damage Your DNA, Study Shows

By Keri Blakinger 09/26/16

The impact can last for decades. 

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Smoking Can Damage Your DNA, Study Shows

Smoking cigarettes can damage your DNA for decades, according to a study in the October issue of the journal Circulation: Cardiovascular Genetics.

“Our study has found compelling evidence that smoking has a long-lasting impact on our molecular machinery, an impact that can last more than 30 years," researcher Roby Joehanes of Hebrew SeniorLife and Harvard Medical School said in a statement.

In a broad study of nearly 16,000 people, researchers found that smoking alters DNA through a process called methylation, which can make cancer-causing changes to genes, according to NBC News. Genetic damage is responsible for medical problems like heart disease and cancer.

“The encouraging news is that once you stop smoking, the majority of DNA methylation signals return to never smoker levels after five years, which means your body is trying to heal itself of the harmful impacts of tobacco smoking,” Joehanes said.

The study’s authors found that, among smokers, almost a third of the entire genome showed evidence of methylation. But once former puffers go tobacco-free, most of those changes revert back to normal patterns within about five years.

Some of the damage stuck around a little longer, though. The smoking-related shifts in 19 genes—including one linked to lymphoma—could last for up to 30 years, the study showed.

“These results are important because methylation, as one of the mechanisms of the regulation of gene expression, affects what genes are turned on, which has implications for the development of smoking-related diseases,” said Dr. Stephanie London, deputy chief of the Epidemiology Branch at the National Institute of Environmental Health Sciences, National Institutes of Health. “Equally important is our finding that even after someone stops smoking, we still see the effects of smoking on their DNA.”

Although the study may be bad news for current and former smokers, it could be good news for the treatment of certain smoking-related conditions, as researchers may now have better ideas for therapeutic targets. 

Cigarette smoking is the number one preventable cause of death in the United States, according to the Centers for Disease Control and Prevention. More than 480,000 U.S. deaths are caused by smoking every year—which is more than those caused by HIV, drug use, drinking, car crashes and gun deaths combined.

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Keri Blakinger is a former drug user and current reporter living in Texas. She covers breaking news for the Houston Chronicle and previously worked for the New York Daily News and the Ithaca Times. She has written about drugs and criminal justice for the Washington Post, Salon, Quartz and more. She loves dogs and is not impressed by rodeo food. Find Keri on LinkedIn and Twitter.

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