Efficacy and tolerability of a high loading dose (25,000 IU weekly) vitamin D3 supplementation in obese children with vitamin D insufficiency/deficiency

BACKGROUND: The recommended dose of vitamin D supplementation of 400 IU/day might be inadequate to treat obese children with vitamin D insufficiency. Therefore, we tested the efficacy and tolerability of a high loading dose vitamin D3 supplementation of 25,000 IU weekly in multiethnic obese children, 8-18 years of age, with vitamin D insufficiency/deficiency.

METHODS: Fasting blood samples were drawn for the assessment of vitamin D. Vitamin D-insufficient/-deficient children (<50 nmol/l) were supplemented, using a high loading dose of 25,000 IU weekly, and measured again 9 weeks later. Vitamin D supplementation was considered effective and tolerable when an increase to vitamin D sufficiency (25(OH)D >50 nmol/l) was reached in >75% without side effects nor reaching toxic levels.

RESULTS: In total, 109 children (mean ± SD age 11.1 ± 3.0, 34.2% boys, 90.8% obese) received vitamin D supplementation. In 84.4% of the children, the vitamin D status improved from insufficiency/deficiency (<50 nmol/l) to sufficiency (≥50 nmol/l). The majority of children that did not reach vitamin D sufficiency reported non-compliance. No side effects were reported, and the highest level reached was far below the threshold for toxicity.

CONCLUSION: A high loading dose vitamin D3 supplementation is effective and well-tolerated in our cohort of multiethnic obese children with vitamin D insufficiency/deficiency.