Response to Weekly Oral Vitamin D Supplementation in Children Living with Obesity versus those with Normal BMI

Individuals living with obesity are prone to vitamin D deficiency. On supplementing vitamin D, lower serum 25(OH)D levels may be achieved in them. The present study aimed to compare the change in serum 25(OH)D after supplementation with vitamin D in children living with obesity versus children with normal body mass index (nBMI) and to study its correlation with BMI and fat mass (FM).

Sixty vitamin D-deficient children (Groups 1-30 with BMI ≥23^rd adult equivalent of Indian Academy of Pediatrics BMI charts and Groups 2-30 nBMI children) were administered oral vitamin D3 (60,000 IU weekly for five doses) in an open-labelled nonrandomised controlled trial. Serum 25(OH)D was measured before intervention and at days 7, 30 and 90 post-intervention, along with serum and urine calcium.

The change/rise in 25(OH)D was significantly less in Group 1at days 7, 30 and 90. At day 30, the rise was 25% lower than in Group 2 and had a negative correlation with BMI (r = -0.412, P = 0.001) and FM (r = -0.452, P = 0.002). The mean circulating levels at days 30 and 90 were 20% lower in Group 1. The area under curve of the 25(OH)D profile in the two groups demonstrated a significant difference between the groups (3776.9 ± 780.0 in Group 1 vs 4857.9 ± 1267.8 in Group 2, P = 0.0002). Transient hypervitaminosis (without hypercalcaemia or hypercalciuria) was seen in 2/28 of Group 1 and 8/30 of Group 2 (only at day 7).

The higher BMI children had a 25% lower rise in serum 25(OH)D levels.