But if you smoke and want to quit, doing so could still help you avoid RA, new research shows.
The study, published in Arthritis Care & Research, found that women who quit smoking saw their risk for developing seropositive RA start to decline about five years later. And their risk continued to decrease as long as they stayed smoke-free, falling by 37 percent after 30 years.
Seropositive RA is the most common form of RA, according to the researchers. It also tends to do the most damage to joints. But quitting smoking didn't seem to change the women's risk of getting a less-common type of RA, called seronegative RA. (Incidentally, this finding may suggest that seronegative and seropositive RA are actually different diseases with different causes, according to the study's authors.)
Why does smoking raise RA risk?
In RA, a person's own immune system mistakenly turns against the body. It's not clear how smoking may make this more likely to happen. But some researchers think it may promote substances, called autoantibodies, that the body makes and uses to attack the joint tissues, as well as boost inflammation.
But what does seem clearer now is this: If you smoke, quitting may help reduce your risk for RA—not to mention many other diseases. And the sooner you become a nonsmoker and stay that way, the better. That's because, in this study, former smokers didn't see the full benefit of their healthy decision until years to decades later.
Researchers hope to involve other people, including men, in future studies of smoking cessation and RA.