Smoking affects DNA permanently, according to a new study that found effects on a small amount of DNA up to 30 years after quitting, though many of the changes smoking causes fade.
The study, published in the American Heart Association Journal “Circulation: Cardiovascular Genetics,” showed that smoking caused DNA methylation, or changes in the way DNA are expressed or activated. DNA methylation is thought to be responsible for many diseases like cancer, osteoporosis, and heart problems. It isn’t that gene methylation causes DNA to change, but that it causes changes in how the DNA is expressed.
More than 2,500 methylations were found in smokers, which can affect more than 7,000 genes, or about one-third of known human genes. Many of the genes affected were linked to heart disease and to cancers related to smoking.
Those who quit reversed most of their methylation within five years, but researchers found that changes in some genes, including the gene linked to lymphoma, lasted 30 years. Only about 185 of the methylated locations showed continued differences years after quitting, but these had the potential to cause disease long after smoking habits had changed for the better, Reuters reported.
Senior author of the study Dr. Stephanie London said the study is a motivation to change an ingrained habit.
“Stop smoking now because many, many, many of the effects of smoking will go away,” she said .
According to WebMD, this and other studies may lead to the development of better tests to determine who has smoked in the past. Currently, there is no test to determine whether a person had smoked years earlier.