Vitamin D Deficiency and Its Association with Recurrent Wheeze in Toddlers

Abstract

Background: Recurrent wheezing is a frequent respiratory issue in childhood, and may be affected by nutrition, environment, infection, and genetic factors. Vitamin D has a role in immune regulation and in the function of respiratory epithelial cells and in the regulation of airway inflammation. Thus, low levels of vitamin D may make young children more vulnerable to frequent wheezing.

Objective: To determine the frequency of vitamin D deficiency among toddlers and assess its association with recurrent wheeze.

Material and Methods: This hospital-based comparative cross-sectional study was conducted at the Department of Paediatrics, Nowshehra Medical College, Nowshehra, from January 2023 to July 2023. 77 toddlers aged between 12-36 months were recruited using non-probability consecutive sampling. The participants were divided into two groups: recurrent-wheeze and non-recurrent-wheeze. A structured proforma was used to gather the demographic, nutritional, clinical and environmental data. Serum 25-hydroxyvitamin D was analysed and vitamin D status was defined as deficient, insufficient and sufficient. Appropriate statistical tests were used for group comparisons and binary logistic regression was used to determine independent predictors of recurrent wheeze. A p-value of < 0.05 was defined as statistically significant.

Results: The mean age of the participants was 25.8 ± 7.1 months, and 43 (55.8%) were boys. Recurrent wheeze was present in 42 (54.5%) toddlers. Vitamin D deficiency was identified in 44 (57.1%) participants, insufficiency in 20 (26.0%), and sufficiency in 13 (16.9%). The mean serum vitamin D level was significantly lower in toddlers with recurrent wheeze than in those without recurrent wheeze, at 16.8 ± 6.7 ng/mL and 25.6 ± 9.4 ng/mL, respectively (p < 0.001). Vitamin D deficiency was present in 73.8% of children with recurrent wheeze compared with 37.1% of those without recurrent wheeze (p = 0.001). After adjustment for potential confounders, vitamin D deficiency remained independently associated with recurrent wheeze (adjusted OR = 4.12; 95% CI: 1.42–11.94; p = 0.009).

Conclusion: Vitamin D deficiency was common among toddlers and was independently associated with recurrent wheeze. Deficient children also experienced more frequent episodes, emergency visits, and night-time respiratory symptoms. Assessment of vitamin D status may be beneficial in toddlers presenting with repeated wheezing, although prospective studies are required to determine whether vitamin D supplementation can reduce future wheezing episodes.

Keywords: Vitamin D deficiency; recurrent wheeze; toddlers; 25-hydroxyvitamin D; bronchiolitis; airway inflammation.