Vitamin D deficiency linked to severe asthma in children

Insufficient blood vitamin D concentrations could be the reason why children with asthma experience worse lung function and more severe symptoms, a new UK study says.

In the study, potential relationships between serum vitamin D (25-hydroxyvitamin D3) concentration and asthma were investigated in 86 children (mean age 11.7 years), 36 of whom had severe, therapy-resistant asthma (STRA), 26 who had moderate asthma and 24 who had no asthma (1). In addition to vitamin D levels, lung function, use of medication and symptoms were tabulated for all the participants. Moreover, airway tissue samples were collected from children with severe asthma. The study results showed that children with STRA had significantly lower levels of vitamin D, a greater use of asthma medications, more exacerbations of symptom and worse lung function when compared with children in the other two groups. The tissue samples also revealed an increase in airway smooth muscle.

According to the researchers, their findings suggest that lower levels of vitamin D in children with STRA contribute to an increase in airway smooth muscle mass, which could make breathing more difficult and exacerbate asthma symptoms. Recent studies have highlighted the role of vitamin D and vitamin D receptor (VDR) in regulation of several genes that are involved in inflammation, immunity, as well as in cellular proliferation and differentiation (2). Thus, treating vitamin D deficiency could help prevent or reduce the structural changes that occur in the airway smooth muscle, which in turn may help reduce asthma-related symptoms and improve overall lung function.

According to a recent report, 70 percent of school-age children do not get enough vitamin D (3). In addition to placing children at risk for heart disease, weak bones and high blood pressure, vitamin D deficiency now appears to be detrimental for children with severe asthma. Childhood asthma is a major problem, affecting 10 percent of all children. Standard treatment is low doses of corticosteroids. However, 5 to 10 percent of children are unaffected by this approach. These children have severe therapy-resistant asthma and as a result suffer more asthma attacks, need more healthcare services and experience more asthma-related problems than do children with less severe asthma.

1. Gupta A. et al. Relationship between serum vitamin D, disease severity and airway remodeling in children with asthma. American Journal of Respiratory and Critical Care Medicine. Online publication September 2011.
2. Sundar I. K. and Rahman I. Vitamin D and susceptibility of chronic lung diseases: role of epigenetics. Front Pharmacol. 2011; 2:50.
3. Melamed M. L. et al. Prevalence and associations of 25-hydroxyvitamin D deficiency in children and adolescents in the United States: results from NHANES 2001-2004. Pediatrics. 2009; 124(3):e362–370.