Low Vitamin D, Asthma Are Risk Factors for Decreased Childhood Lung Function

Both low gestational 25-hydroxyvitamin D levels (25[OH]D) and childhood asthma are risk factors for decreased lung function in early childhood, according to the results of a recent study published in the Journal of Allergy and Clinical Immunology.

In a post hoc analysis of the Vitamin D Antenatal Asthma Reduction Trial (VDAART; ClinicalTrials.gov Identifier: NCT00920621), researchers examined the effect of vitamin D levels and childhood asthma phenotypes on lung function in childhood. They measured plasma 25[OH]D at 10 to18 and 32 to 38 gestational weeks in mothers during pregnancy and in children at ages 1 and 3 years. Children were categorized into 3 clinical asthma phenotypes: 1) asymptomatic/infrequent wheeze; 2) early transient wheeze; and 3) asthma at 6 years of age. In the primary study outcome, lung function was assessed with impulse oscillometry at ages 4, 5, and 6 years and with spirometry at ages 5 and 6 years.

A total of 570 mother and child pairs were included in the post hoc analysis. Mean gestational 25(OH)D levels showed a positive trend with offspring lung function at ages 4, 5, and 6 years, indicating an increasing level of lung function with increasing 25(OH)D levels (P =.008 for forced expiratory volume in 1 second [FEV₁] and P =.002 for forced vital capacity [FVC]). Furthermore, children with asthma at 6 years of age had lower levels of lung function from 4 to 6 years of age than either the asymptomatic or infrequent wheeze groups (P <.001 for both child respiratory resistance at 5 Hz and FEV₁).

“This study provides evidence that low gestational vitamin D level and childhood asthma phenotype are important and independent risk factors for decreased childhood lung function from 4 to 6 years of age,” the study authors wrote. “Low gestational vitamin D level appears as an important modifiable risk factor for impaired lung function in early childhood.”

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.

Reference

Knihtilä HM, Stubbs BJ, Carey VJ, et al. Low gestational vitamin D level and childhood asthma are related to impaired lung function in high-risk children. J Allergy Clin Immunol. Published online January 22, 2021. doi:10.1016/j.jaci.2020.12.647