July 23, 2012

Smokers Need Vitamin D

(Ivanhoe Newswire) - Three quarters of American adults are considered vitamin D deficient. Consistent research has shown a lack of vitamin D can cause to a variety of health issues, including impairment of lung function for smokers.

Vitamin D deficiency is associated with worse lung function and more rapid decline in lung function over time in smokers, suggesting that vitamin D may have a protective effect against the effects of smoking on lung function according to a new study.

"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," lead author Nancy E. Lange, M.D., MPH, of the Channing Laboratory, Brigham and Women's Hospital was quoted as saying. "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," she added.

In the study, vitamin D levels were assessed at three different time points between 1984 and 2003, and lung function was assessed concurrently with the measurement of breath.

In vitamin D deficient subjects, for each one unit increase in pack-years of smoking, mean forced expiratory volume in one second (FEV1) was 12 ml lower, compared with a mean reduction of 6.5 ml among subjects who were not vitamin D deficient. In longitudinal models, vitamin D deficiency exacerbated the effect of pack years of smoking on the decline in FEV1 over time.

No significant effect of vitamin D levels on lung function or lung function decline were observed in the overall study cohort, which included both smokers and non-smokers.

"Our results suggest that vitamin D might modify the damaging effects of smoking on lung function," Dr. Nancy E. Lange was quoted as saying. "These effects might be due to vitamin D's anti-inflammatory and anti-oxidant properties."

The study has some limitations, including the fact that the data is observational only and not a trial. Also, vitamin D levels fluctuate over time and that the study has limited generalizability due to the cohort being all elderly men.

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

Source: American Journal Of Respitory And Critical Care Medicine, July 2012