Researchers in Boston found that vitamin D deficiency in smokers is associated with worse lung function and more rapid decline in lung function over time.
The research published in the American Journal of Respiratory and Critical Care Medicine examined 626 adult elderly white men from the Normative Aging Study. Vitamin D levels were tested 3 different times between 1984 and 2003, and lung function was tested concurrently.
The authors found that in vitamin D deficiency participants (≤20 ng/mL), for each 1 unit increase in pack-years of smoking, FEV1 (mean forced expiratory volume in one second) decreased by 12 ml. While participants who were not D deficient, had FEV1 scored of 6.5 ml lower.
“This suggests that maintaining vitamin D sufficiency may have a protective effect against the more rapid lung function decline seen in smokers,” Said lead author Dr Nancy E. Lange, MD, PhD.
The authors did not find a significant association between vitamin D deficiency and lung function among the whole cohort, which included smokers and non-smokers.
The researchers attribute these beneficial effects to vitamin D’s anti-inflammatory and anti-oxidant properties.
Limitations of the study were of course, the data is simply observational, not randomized or controlled. Secondly, the vitamin D levels were only tested 3 times over a 20 year period, so the study does not account for possible fluctuation of levels. Lastly, the cohort used in the study was elderly white men, so we cannot generalize to other populations.
The authors conclude, “Long-term interventional studies of vitamin D supplementation, including several currently ongoing trials in COPD, will be essential to further explore these associations.”