They looked at the relationship  between having too little vitamin D in the body, smoking, lung function, and the rate of lung  function decline over a 20-year period in a cohort of 626 adult white men. Vitamin D levels were assessed at three different time points between 1984 and 2003, and lung function was assessed with spirometry.

They found that those who had enough vitamin D over the period of the study had healthier lungs with less decline of function that those with too little of the vitamin. “Our results suggest that vitamin D might modify the damaging effects of smoking on lung function,” said lead author Dr Nancy Lange of the Channing Laboratory, Brigham and Women’s Hospital, Boston, MA, USA. “These effects might be due to vitamin D’s anti-inflammatory and anti-oxidant properties.”

Since the study only explored the impact of vitamin D deficiency among an elderly male cohort further investigation is needed to explore the impact of vitamin D in other cohorts. “If these results can be replicated in other studies, they could be of great public health importance,” said Dr Lange.  “Future research should also examine whether vitamin D protects against lung damage from other sources, such as air pollution.”

Although vitamin D may have benefits for smokers’ lung health, Alexander C. White MD, chair of the American Thoracic Society’s Tobacco Action Committee cautions that “while these results are intriguing, the health hazards associated with smoking far outweigh any protective effect that vitamin D may have on lung function. First and foremost, patients who smoke should be fully informed about the health consequences of smoking and be given all possible assistance to help them quit smoking.”

The findings were published online ahead of print publication in the American Thoracic Society’s American Journal of Respiratory and Critical Care Medicine.

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