When smokers quit, they’re often told they have a lower risk for many illnesses and complications the longer they stay off cigarettes. However, the American Heart Association this week released the findings of an important new study showing that tobacco can leave a lasting legacy on the surface of smokers’ DNA.

Now, it’s believed that a smoker may always be at a higher risk for certain diseases and conditions — as that person has altered his or her DNA. The study appeared this week in an American Heart Association journal.

Bottom line? Don’t ever start smoking — and if you smoke now, quit immediately.

Even after someone stops smoking, the effects of smoking remain on their DNA.

The process is called DNA methylation. It’s how cells control gene activity and it often modifies the function of genes. DNA methylation might not only reveal a person’s smoking history, it could also help researchers develop targeted new therapies for diseases associated with smoking.

“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.” That’s from a statement by Stephanie J. London, M.D., deputy chief of the epidemiology branch at the National Institute of Environmental Health Sciences in North Carolina. “Equally important is our finding that even after someone stops smoking, we still see the effects of smoking on their DNA.”

Smoking remains the leading preventable cause of death worldwide, despite a decline in smoking in many countries. Even decades after quitting, former smokers are at long-term risk of developing diseases including some cancers, chronic obstructive pulmonary disease (COPD), and stroke.

Related: Cigarette Smoking is Ugly and Getting Uglier

The researchers compared DNA methylation in current and former smokers to those who never smoked. Among their findings — the majority of DNA methylation sites returned to levels seen in never-smokers within five years of quitting smoking. However, some DNA methylation sites persisted even 30 years after quitting. The most common health risks to linger include cardiovascular disease and certain cancers.

“The strongest motivators [to quit] tend to be more immediate risks, such as ‘I just had a heart attack,’” said one cessation expert.

Who do you think would win the Presidency?

By completing the poll, you agree to receive emails from LifeZette, occasional offers from our partners and that you've read and agree to our privacy policy and legal statement.

While some of this has been known, Dr. Doug Jorenby, director of clinical services at University of Wisconsin Center for Tobacco Research and Intervention, said the study was of interest because it examined a number of smoking-related health risks. It also helped quantify how long risks due to DNA changes could persist. More than 16,000 people took part in the research.

“It certainly provides yet more motivation [to quit], but the strongest motivators tend to be more immediate risks, such as ‘I just had a heart attack.’ Some people are more fatalistic about their own health, but can be motivated to quit to protect others, as in the case of parents or grandparents who quit so as not to expose babies to secondhand smoke,” Jorenby told LifeZette. “That is a more immediate motivator [with immediate benefits] than quitting so you don’t pass on genetic risks 30 years from now.”

Different people will quit for different reasons, Jorenby added — and motivation can change quickly. Perhaps the biggest takeaway here is that effective treatment resources need to be available to those who want help.

“Having someone come in for a clinic visit in two months is not effective. That’s why having so many different ways to access evidence-based treatments is essential.”

[lz_ndn video=31430991]