Some Smoking Damage Is Permanent, Study
Although most cell damage caused by smoking improves over time, some does not. A large study involving 16,000 former smokers showed that changes to DNA, which can inactivate genes and/or cause them to function differently, are permanent. These genetic changes can cause cancer, heart disease, and other diseases.
The study showed that smoking damages more than 7,000 genes—one-third of the total number of known human genes—many of which are linked to smoking-related health problems. When a person quits smoking, DNA damage improves significantly—but not completely—within about 5 years. According to researchers, the harmful effects of smoking on about 19 genes, including a gene linked to lymphoma, can last 30 years or more.
Worldwide, smoking is a primary cause of preventable diseases that claim about 6 million lives each year. Quitting—even after years of smoking and at any age—is beneficial, but it doesn’t clear the slate.
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