FRIDAY, July 20 (HealthDay News) -- Among smokers, lung function may decline faster in those who have a vitamin D deficiency than in those with normal vitamin D levels, a new study suggests.
However, although boosting levels of vitamin D may offer some protection to the lungs from the effects of smoking, it won't prevent deteriorating lung function or smoking-related health problems, such as heart disease, stroke and cancer, the researchers warned.
"Vitamin D, possibly due to its antioxidant and anti-inflammatory effects, could provide a small amount of protection against lung damage that occurs from smoking," said lead researcher Dr. Nancy Lange, of the Channing Laboratory at Brigham and Women's Hospital in Boston.
"If these findings are replicated in other studies and interventional trials, vitamin D supplementation could have the potential to provide some protection against the damage to lung function that is due to smoking," she said.
Lange emphasized that the effect was small and "the most important intervention, for both lung and overall health, is for people to stop smoking."
The report was released online July 19 in advance of print publication in the American Journal of Respiratory and Critical Care Medicine.
For the study, Lange's team collected data on more than 600 white men who were part of an ongoing, long-term study on aging. Among these men, the researchers looked for an association between vitamin D and lung function.
Over 20 years of follow-up, the investigators found that lung function among smokers with normal levels of vitamin D deteriorated less than that of smokers with below normal levels of this vitamin.
Vitamin D, however, does not have a significant effect on lung function for either good or bad when looking at smokers and nonsmokers combined, the researchers noted.
Limitations of the study include its observational design and changing levels of vitamin D over time. In addition, the findings may not apply to other groups as all of the participants were older men, the study authors pointed out.
Dr. Arunabh Talwar, director of the advanced lung disease program at North Shore-LIJ Health System in Great Neck, N.Y., said that "this tells us that in smokers, if we can prevent vitamin D deficiency, we can slow decline in lung function."
Although everybody loses some lung function as they age, smokers lose lung function faster than nonsmokers, Talwar noted. "Vitamin D deficiency is probably making it worse," he said.
Talwar stressed that taking vitamin D is not a substitute for quitting smoking. Smokers are also at increased risk for heart attack, stroke and cancer, he noted.
Another expert, Dr. Michael Holick, a professor of medicine, physiology and biophysics at Boston University School of Medicine, added that "this is consistent with other findings about vitamin D and lung function."
For example, children who are vitamin D deficient are more likely to develop wheezing and asthma, he pointed out.
"It's not a surprise that smokers who are vitamin D deficient have poorer lung function," Holick said. There are also some studies that suggest that smoking actually decreases vitamin D levels, he noted.
"It may be that vitamin D plays a role in maintaining healthy lung tissue," Holick said. But, he added, "I am not recommending that you take vitamins to counteract the negative effects of smoking on lung function."
While the study found an association between vitamin D and smokers' lung function, it did not prove a cause-and-effect relationship.
SOURCES: Nancy E. Lange, M.D., M.P.H., Channing Laboratory, Brigham and Women's Hospital, Boston; Arunabh Talwar, M.D., director, advanced lung disease program, North Shore-LIJ Health System, Great Neck, N.Y.; Michael F. Holick, M.D., Ph.D., professor, medicine, physiology and biophysics, Boston University School of Medicine; July 19, 2012, American Journal of Respiratory and Critical Care Medicine, online
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