At this point, everyone knows smoking does not have one health benefit.
According to a recent study by researchers at the US National Institute of Environmental Health, smoking is the leading preventable cause of death globally.
This finding could shed more light on why smoking is linked to the development of so many diseases.
Researchers evaluated results from blood samples taken from almost 16,000 people in 16 studies. They found that the genes of people who stopped smoking mostly recovered within five years of quitting, but not completely.
Senior scientific advisor for the American Lung Association Dr. Normal Edelman commented on these findings by saying,
Researchers saw that in some cases, even 30 years after quitting, some genetic changes remained.
The team focused on the process of DNA methylation, which are genetic changes that only alter how they're expressed, not their underlying code.
Based on their research, the pattern of methylation in smokers changed over 7,000 genes, which is one-third of known human genes. Several of these genes are linked to cancers and heart disease that smoking causes.
This gives researchers a big clue about why people are still at risk of disease even years after they've quit smoking.
Senior author Dr. Stephanie London said,
It's just scary to think that even after you stop smoking for years, the damage can stay with you for the rest of your life.