The Role of Vitamin D in Chronic Obstructive Pulmonary Disease, Asthma and Other Respiratory Diseases

Abstract There has been a growing interest in recent years in the extraosseous effects of vitaminD. In this article, we review the physiology of vitaminD, the physiopathological effects associated with vitaminD deficit and the available evidence on its etiopathogenic role in respiratory diseases. Given the pleiotropic actions of vitaminD, it is biologically plausiblethat the deficit of this vitamincould play a pathogenic role in the development of various respiratory diseases. However, the many epidemiological studies that have shown an association between low vitaminD levels and a higher risk of developing various respiratory diseases, or a poorer prognosis if they do appear, were unable to show causality. Post hoc analyses of some clinical trials, particularly in chronic obstructive pulmonary disease (COPD) and asthma, appear to suggest that some patient subtypes may benefit from correction of a vitaminD deficit. In this respect, it would be interesting to determine if the interindividual differences found in the effect of vitaminD deficit and responses to correcting this deficit could be explained by the genetic variants involved in vitaminD metabolism. Ultimately, only appropriately designed clinical trials will determine whether 25-OH D supplements can prevent or improve the course of the various respiratory diseasesin which an epidemiological association between prognosis and vitaminD deficit has been described.