An analysis of almost 16,000 blood samples from smokers, former smokers and nonsmokers found that tobacco smoke leaves a lasting legacy of people's addiction on the surface of their DNA. The modification identified in this study was DNA methylation, in which a molecule called a methyl group sits on the surface of DNA and influences whether genes are active or silent. Studies have showed that smoking can cause these surface changes to DNA and that these changes could be used to measure the risk of particular diseases, such as 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." "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."

Source: CNN September 22, 2016 18:00 UTC