Response to vitamin D3 supplementation in obese and non-obese Caucasian adolescents.

Background/aims: Vitamin D deficiency is highly prevalent in obese children, and obese children tend to respond poorly to vitamin D supplementation. The objective of the study was to compare the response to vitamin D(3) supplementation (2,000 IU once daily for 12 weeks) between obese and non-obese Caucasian adolescents.

Methods: The study design was open label non-randomized. It was carried out at a single center. Eighteen obese adolescents (aged 12-18 years) and the same number of age-, gender- and season-matched non-obese adolescents received vitamin D(3) (2,000 IU/day) orally for 12 weeks. Total serum 25-hydroxyvitamin D [25(OH)D], parathyroid hormone, calcium and phosphorus were measured at baseline and at the end of the 12-week period.

Results: The mean baseline 25(OH)D level was higher in the non-obese compared to the obese subjects (mean 28.9 vs. 25.2 ng/ml; p = 0.029). The increment in 25(OH)D levels following vitamin D supplementation was significantly lower in the obese adolescents (mean change 5.8 vs. 9.8 ng/ml; p = 0.019).

Conclusions: Higher doses of vitamin D are required to treat vitamin D deficiency in obese adolescents compared to their non-obese peers.