Vitamin D Deficiency in Children with Asthma and Overweight/Obesity in Qatar

Childhood asthma, obesity, and vitamin D deficiency are all highly prevalent in Qatar, and children with concurrent asthma and obesity experience greater disease severity and poorer treatment response than those with asthma alone. Although vitamin D deficiency has been linked to asthma, the combined effect of co-existing asthma and overweight/obesity on vitamin D status has not been characterized in this population, warranting further investigation.

This cross-sectional observational study assessed serum 25-hydroxyvitamin D levels in children aged 6-17 years, residing in Qatar. A total of 364 children were divided into four groups: children with normal weight and asthma (NW-A), children with overweight/obesity and asthma (OO-A), children with overweight/obesity and no asthma (OO), and children with normal weight and no asthma (NW). Between-group differences were assessed using chi-square, Dunn (Bonferroni-corrected), and Spearman correlation tests, and a multivariable logistic regression model adjusted for age, sex, BMI, and atopy was used to examine the association between asthma and vitamin D status.

Children in all the four groups demonstrated a high prevalence of vitamin D deficiency (<50 nmol/L), regardless of asthma or BMI. Vitamin D deficiency was present in 81.1% of OO, 73.9% OO-A, 68.3% of NW, and 66.3% of NW-A, with no statistically significant difference across groups. Vitamin D levels were similar between NW-A and OO-A, but OO group had significantly lower levels. A negative correlation between BMI and vitamin D levels was observed in OO-A (ρ=-0.279, p=0.008) and OO (ρ=-0.266, p=0.009), but not in normal-weight children. Multivariable logistic regression showed no significant association between vitamin D levels and asthma status.

Higher BMI was associated with lower serum vitamin D levels in overweight/obese children, independent of asthma status, whereas asthma was not independently associated with vitamin D deficiency. Given the cross-sectional design, these findings indicate associations rather than causal relationships. The high prevalence of vitamin D deficiency across all study groups highlights a substantial public-health concern and supports the value of routine screening, nutritional and lifestyle measures, and where indicated, vitamin D supplementation, in pediatric health management in Qatar, pending confirmation from longitudinal and interventional studies.