New Orleans — Approximately half of children with asthma were deficient in vitamin D in a study of 99 children aged 18 and younger. The findings were presented in a poster at the annual meeting of the American Academy of Allergy, Asthma and Immunology.
Previous studies have indicated that vitamin D insufficiency contributes to the pathophysiology of allergic disease, but data on vitamin D’s impact on children with allergies and asthma are limited, said Dr. Daniel Searing of National Jewish Health in Denver, Colo.
In this study, Dr. Searing and colleagues identified 99 children who had asthma, atopic dermatitis, and/or a food allergy. The researchers assessed vitamin D by measuring serum 25-hydroxyvitamin D levels.
Overall, 47% of the patients had insufficient levels of vitamin D (less than 30 ng/mL). The median vitamin D level was 31 ng/mL.
To assess the impact of vitamin D on inflammation, the researchers cultured peripheral blood mononuclear cells (PBMC) from 11 patients using either 10 nM vitamin D or a placebo medium for 24 hours, and supplemented them with either 10 or 100 nM of dexamethasone for the last 3 hours of culturing. Next, they measured mitogen-activated protein kinase phosphatase-1 (MKP-1) and interleukin-10 (IL-10.)
“Vitamin D enhances glucocorticoid induction of MKP-1 and IL-10 in asthmatic PBMC in vitro,” the researchers wrote. Vitamin D addition can enhance the activity of dexamethasone more than 10-fold, they added.
“The relationship between vitamin D and corticosteroid pathways, as well as its effect on the inflammatory response, is not fully understood,” the researchers emphasized. But the results suggest that vitamin D supplementation may enhance the anti-inflammatory function of corticosteroids in asthma patients, they noted.
Median vitamin D levels were significantly lower in children taking inhaled corticosteroids (29 ng/mL), oral corticosteroids (25 ng/mL) and long-acting beta-agonists (25 ng/mL), compared with children who were not taking inhaled corticosteroids, oral corticosteroids, or long-acting beta-agonists (35 ng/mL, 32 ng/mL, and 34 ng/mL, respectively)
In addition, median vitamin D levels were significantly lower in children with positive vs. negative aeroallergen sensitivity to dog dander (29 ng/mL vs. 35 ng/mL) and house dust mites (27 ng/mL vs. 31 ng/mL).
Dr. Searing had no financial conflicts to disclose. The study was supported in part by a grant from the National Institutes of Health.