The role of Vitamin D in the development, exacerbation, and severity of asthma and allergic diseases

Abstract

The prevalence of asthma and allergic disease continues to increase throughout the world, but particularly in westernized countries and countries that are rapidly transitioning to a westernized way of living. Since vitamin D deficiency has become prevalent, vitamin D likely has a role to play in the rise in prevalence of these disorders. However, there are two countervailing hypotheses regarding this role. The first hypothesis is that introduction of fortification of foods with vitamin D contributed to the allergy epidemic, due to the timing of this widespread fortification relative to the recognition of the asthma and allergy epidemic. However, given the documented deficiency in circulating vitamin D in various populations despite the forti fi cation of foods, and the development of technologies that have made it more attractive for humans to spend more time indoors, the other hypothesis takes the opposite view that it is vitamin D deficiency that has made populations susceptible to the development of these disorders. This chapter will review the epidemiology of asthma and allergies, the epidemiology of vitamin D de fi ciency, the potential mechanisms by which vitamin D affects asthma and allergy risk, and the studies that have been performed to investigate the role of vitamin D. Finally, the chapter concludes with some recommendations for future studies.