A research has found compelling evidences that smoking scars your DNA in clear patterns as it has a long-lasting impact on the molecular machinery that can last more than 30 years. Moreover, some damage may stay there forever. But the encouraging news is that once you stop smoking, the majority of DNA methylation signals return to never-smoker levels after five years.
The findings were reported in the American Heart Association journal Circulation:
DNA methylation return to never-smoke levels
“Our study has found compelling evidence that smoking has a long-lasting impact on our molecular machinery, an impact that can last more than 35 years after the people quit, and some appear to stay there forever,” said Hoehanes. “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 added.
Smoking has long-lasting impact on molecular machinery
The researchers studied 15,000 people and found that if people quit smoking, after five years, most of the disease-causing genetic footprints left, fadeout of the body but some appear to stay there forever. The marks are made in a process called methylation. Methylation is an alteration of DNA that can inactivate a gene or change how it functions and may often cause cancer and other diseases. “Our study has found compelling evidence that smoking has a long-lasting impact on our molecular machinery, an impact that can last more than 35 years,” said Roby Joehanes of Hebrew SeniorLife and Harvard Medical School.
Mechanism for long-term effects not well understood
“Even decades after cessation, cigarette smoking confers long-term risk of diseases including some cancers, chronic obstructive pulmonary disease, and stroke,” London’s team wrote. “The mechanisms for these long-term effects are not well understood. DNA methylation changes have been proposed as one possible explanation.”
Even after cessation, effects are seen on DNA
“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 of the National Institute of Environmental Health Sciences, who directed the team. “Equally important is our finding that even after someone stops smoking, we still see the effects of smoking on their DNA,” London said.
Cancer, heart disease caused by genetic damage
Cancer and heart disease are caused by genetic damage, which may be inherited, but most of cases are caused by day-to-day living and smoking is one of the biggest culprits. The team went back to 1970 and studied different researches and blood samples given by 15,000 people thereafter. In all the studies, people had filled out questionnaires about smoking, diet, lifestyle and their health histories and also given blood samples.
In 19 genes, smoking-related changes lasted 30 years
The researchers found that smokers had a pattern of methylation changes, which affects around one-third of known human genes or more than 7,000 genes. Many of the genes linked to heart disease and cancers were known to be caused by smoking. Among those, who quit smoking, most of these changes reverted to the patterns seen in people who never smoked after about five years. But in 19 genes, smoking-related changes lasted 35 years. This include the TIAM2 gene, which is linked to lymphoma.