Vitamin D and Asthma Severity
A study that was published in Allergy, Asthma & Immunology Research (2013 Sept; 5(5): 283-8) looked at the relationship between vitamin D levels and asthma severity. Researchers analyzed 25-hydroxyvitamin D levels in serum collected from 121 asthmatic adults from Costa Rica to investigate the association between vitamin D levels and the severity of their disease. Vitamin D levels below 30 ng/mL, we defined as insufficient. Asthma severity was determined by forced expiratory volume in 1 second (FEV1), and forced vital capacity (FVC). When the population was stratified by vitamin D status, 91% of asthmatic patients with vitamin D levels below 20 ng/mL (n=36) and 74% of patients with vitamin D levels between 20 and 30 ng/mL (n=73) had severe asthma versus 50% of those with vitamin D sufficiency (n=12; P=0.02). Vitamin D insufficiency was associated with a higher risk of severe asthma. High vitamin D levels were associated with a lower risk of hospitalization or emergency department visit during the last year.