In the study, researchers looked at the effects of various lifestyle factors on the risk of Graves' disease among more than 115,000 women. What they found was that women who currently were smokers had were nearly twice as likely to have Graves' disease, when compared with nonsmokers.
The risk was also heightened for heavier smokers. Smoking more than 25 cigarettes a day, for example, raised the risk to nearly three times normal of deeloping Graves' disease.
Quitting smoking reduced risk, and after 10 to 15 years, the risk of Graves' declined substantially, but all past smokers had slightly increased risk of developing Graves' disease.
The other lifestyle factors that were studied -- which included physical activity/exercise, obesity, and use of alcohol -- did not have any correlation to increased risk of Graves' disease.
Ingrid A. Holm; JoAnn E. Manson; Karin B. Michels; Erik K. Alexander; Walter C. Willett; Robert D. Utiger, "Smoking and Other Lifestyle Factors and the Risk of Graves' Hyperthyroidism," Arch Intern Med. 2005;165:1606-1611.