Smoking Can Cause Long-Term DNA Damage, Study Says

But there's hope: If you quit now, the majority will be repaired within five years.


Smoking photo via

A new study says the effects of smoking linger long after the embers fade. But the news isn’t all bad: If you quit now, it says, you could reverse the majority of DNA damage within five years.

The research, conducted by a team from the Hebrew SeniorLife Institute for Aging Research (IFAR), an affiliate of Harvard Medical School, suggests that smoking leaves a “long-term signature” on large swaths of DNA, with damage potentially lasting more than 30 years. “Our study has found compelling evidence that smoking has a long-lasting impact on our molecular machinery,” first author Roby Joehanes said in a statement.

Smoking throws off DNA methylation, a process through which genes are regulated or turned off. When methylation goes wrong, as it often does with smoking in the equation, it may contribute to the formation of conditions including cancer, heart disease, and inflammatory diseases.

But while it appears that smoking-related damage cannot be wiped from every gene, the IFAR research suggests a huge benefit to quitting as soon as possible. According to the study—which examined blood samples from nearly 16,000 people, some current smokers, some former smokers, and some never smokers—the vast majority of methylation signals return to “never smoker” levels within five years of quitting.

“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 in the statement.

It shouldn’t be news that smoking damages the body—in addition to lung cancer and respiratory disease, it’s been linked to type 2 diabetes and other types of cancer—but perhaps this study will motivate you to toss your cigarettes a little sooner. Your DNA may depend on it.