Smokers' Lung Function May Be Protected By Vitamin D Intake

Date: Jul-23-2012Boston researchers have discovered that vitamin D may protect against the effects of smoking on lung cancer function.

The study, published in advance of the print version of the American Thoracic Society's American Journal of Respiratory and Critical Care Medicine.Vitamin D is linked to worse lung function and over time, in a more rapid decline in lung function.

Leading researcher Nancy E.Lange, MD, MPH, of the Channing Laboratory at Brigham and Women's Hospital said:

"We examined the relationship between vitamin D deficiency, smoking, lung function, and the rate of lung function decline over a 20 year period in a cohort of 626 adult white men from the Normative Aging Study. We found that vitamin D sufficiency (defined as serum vitamin D levels of >20 ng/ml) had a protective effect on lung function and the rate of lung function decline in smokers."

The researchers evaluated the participants' vitamin D levels and their lung function, using spirometry on three different occasions between 1984 and 2003. They found that the average forced expiratory volume in one second (FEV1) was 12 ml lower for each 1-unit increase in pack-years of smoking in those with a vitamin D deficiency, compared to an average reduction of 6.5 ml in those whose vitamin D levels were normal. Longitudinal models have demonstrated that over time vitamin D deficiency worsened the effect of pack years of smoking on lower FEV1-levels. The team detected that vitamin D had no substantial impact on lung function or lower lung function in all participants, regardless of whether they smoked or did not.

Dr. Lange said: "Our results suggest that vitamin D might modify the damaging effects of smoking on lung function. These effects might be due to vitamin D's anti-inflammatory and anti-oxidant properties."

The team acknowledges the study's limitations, i.e. that it the study was observational and not a trial and that vitamin D levels fluctuate over time and also that the study was limited to the fact that participants consisted of elderly men only.

Dr. Lange states: "If these results can be replicated in other studies, they could be of great public health importance. Future research should also examine whether vitamin D protects against lung damage from other sources, such as air pollution."

Alexander C. White MS, MD, chair of the American Thoracic Society's Tobacco Action Committee concluded:

"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 in addition be given all possible assistance to help them quit smoking."

Written by Petra Rattue

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