Vitamin D has been investigated for a number of actions in the body and a few studies have shown that circulating blood levels of vitamin D are related to the development of asthma and asthma exacerbations. While the molecular mechanisms underlying this relationship a unsure, more studies will help to define the relationship.
Ahmed SZ, Jaleel A, Hameed K, Qazi S, Suleman A. Does vitamin D deficiency contribute to the severity of asthma in children and adults? J Ayub Med Coll Abbottabad. 2015 Apr-Jun;27(2):458-63. PMID: 26411139.