Effect of age and body mass index on vitamin D level in children with asthma in Riyadh.

Vitamin D deficiency prevalence in children has been rising. Low 25-hydroxyvitamin D3 (25(OH)D3) levels contribute to poor asthma control in children. This study assessed 25(OH)D3 levels in children with asthma from Riyadh with respect to anthropometrics, dietary, and lifestyle variables. Children with asthma (n, 60; 2-17 years) were assessed for serum 25-hydroxy vitamin D3 (25(OH)D3) level and body anthropometrics (weight, height, and body mass index [BMI]). Vitamin D dietary intake, sun exposure, and sociodemographic data were collected using a structured questionnaire. Thirty-one children (52%) had a 25(OH)D3 level < 50 nmol/L, 15 of whom (25%) had a level < 30 nmol/L. 25(OH)D3 level was significantly negatively correlated with age (P < 0.05), weight (P < 0.02), and height (P < 0.05). Children with a 25(OH)D3 level < 30 nmol/L had a significantly higher BMI than children with insufficient and sufficient vitamin D levels (P < 0.01). There was no significant effect of sex on 25(OH)D3 level. Higher 25(OH)D3 level was associated with a greater body area exposure to the sun. This study found that > 50% of the children with asthma had below sufficiency vitamin D levels. The vitamin D screening and supplementation of older and overweight children with asthma is recommended.