Everyone knows that smoking tobacco causes cancer, heart disease, emphysema, and doubles the risk of age-related macular degeneration. However, scientists have recently discovered that smoking can also permanently damage a person’s DNA.
A recent study of 16,000 people revealed that smoking leads to a process called methylation, which is the alteration of DNA to inactivate a gene or change how that gene functions. If a person quits smoking, most of these genetic footprints fade after about five years of being tobacco-free. However, some of these alterations stick around forever.
“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,” said Roby Joehanes, a researcher from Harvard Medical School and Hebrew SeniorLife. “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.”
In their study, researchers found that the pattern of methylation alterations affected more than 7,000 genes, many of which have known links to cancers and heart disease. Among subjects who had quit smoking, most of these changes reverted back to the patterns found in individuals who had never smoked.
Unfortunately, changes that occurred in 19 particular genes, including the one linked to lymphoma, lasted up to 30 years after smoking cessation.
“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 the director of the study, Dr. Stephanie London. “Equally important is our finding that even after someone stops smoking, we still see the effects of smoking on their DNA.”
In other words, quitting can often mean the difference between life and death for a smoker; however, it doesn’t totally wipe the slate clean. Some risks still remain.