Am J Resp Crit Care：维生素D或能阻止吸烟者肺部功能损伤

根据一项来自美国波士顿市研究人员的一项最新研究，维生素D缺乏与吸烟者体内较差的肺部功能和肺部功能随着时间的推移更快速下降存在关联，这就意味着维生素D可能使人们免受因吸烟而对肺部功能产生的不良影响。相关研究成果于2012年7月19日在线发表在American Journal of Respiratory and Critical Care Medicine期刊上。

研究人员以参加标准衰老研究(Normative Aging Study)项目的626名成年白人作为研究对象，研究了维生素D缺乏、吸烟、肺部功能和20年内肺部功能下降之间的关系，发现维生素D充足(定义为血清维生素D水平大于20 ng/ml)对吸烟者的肺部功能和肺部功能下降速率产生保护作用。

在这项研究中，研究人员在1984至2003年之间不同时间点上评估维生素D水平，同时利用肺活量测试(spirometry)来评估肺部功能。在维生素D缺乏的实验参与者中，年吸烟量每增加一个单位意味着1秒用力呼气量(forced expiratory volume in one second, FEV1)降低12 ml，而对维生素D不缺乏的参与者而言，FEV1平均只下降6.5 ml。就纵向而言，随着时间的推移，维生素D缺乏使得年吸烟量对FEV1影响恶化。但是就对这些参与者(包括吸烟者和非吸烟者)的总体研究而言，研究人员没有观察到维生素D水平对肺部功能或肺部功能下降产生显著性影响。

这项研究也存在一些限制，如这些数据只是根据观察而得来的，而不是开展临床试验而得来的，以及维生素D随着时间的推移会发生变化，另外因为参与者全部都是老年人，所以这项研究的普遍性有限。

本文编译自Vitamin D may protect against lung function impairment and decline in smokers

doi: 10.1164/rccm.201110-1868OC
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Vitamin D deficiency, Smoking, and Lung Function in the Normative Aging Study

Nancy E. Lange1⇓, David Sparrow2, Pantel Vokonas3 and Augusto A. Litonjua

Rationale: Vitamin D has immunomodulatory and anti-inflammatory effects which may be modified by cigarette smoke and affect lung function. Objectives: To examine the effect of vitamin D deficiency and smoking on lung function and lung function decline. Methods: 626 men from the Normative Aging Study had 25-hydroxyvitamin D levels measured at 3 different times between 1984 and 2003 with concurrent spirometry. Vitamin D deficiency was defined as serum level ≤ 20ng/ml. Statistical analysis was performed using multivariable linear regression and mixed effects models. Measurements and Main Results: In the overall cohort, there was no significant effect of vitamin D deficiency on lung function nor on lung function decline. In both cross-sectional and longitudinal multivariable models there was effect modification by vitamin D status on the association between smoking and lung function. Cross-sectional analysis revealed lower lung function in current smokers with vitamin D deficiency (FEV1, FVC, and FEV1/FVC, p≤ 0.0002) and longitudinal analysis showed more rapid rates of decline in FEV1 (p=0.023) per pack-year of smoking in subjects with vitamin D deficiency as compared to subjects who were vitamin D sufficient. Conclusions: Vitamin D deficiency was associated with lower lung function and more rapid lung function decline in smokers over 20 years in this longitudinal cohort of elderly men. This suggests that vitamin D sufficiency may have a protective effect against the damaging effects of smoking on lung function. Future studies should seek to confirm this finding in the context of smoking and other exposures that affect lung function.