Effect of Vitamin D<sub>3</sub> Supplementation on Serum 25(OH)D, Lipids and Markers of Insulin Resistance in Obese Adolescents: A Prospective, Randomized, Placebo-Controlled Pilot Trial

Abstract

BACKGROUND/AIMS: To determine the effect of vitamin D3 supplementation on 25-hydroxyvitamin D [25(OH)D], lipid profile and markers of insulin resistance in obese adolescents. METHODS: In this double-blind, randomized, placebo-controlled trial, 58 obese adolescents (n = 58; 12-18 years of age) received either vitamin D3 (2,000 IU/day) or placebo for 12 weeks. Total 25(OH)D, fasting plasma glucose, insulin and lipid profile were measured at baseline and following supplementation. RESULTS: The trial was completed by 44/58 enrolled participants. At the end of the 12 weeks, total serum 25(OH)D concentrations increased to a modest degree (median 6 ng/ml) in the vitamin D-supplemented group (p < 0.001). Supplementation showed no detectable changes in fasting plasma glucose, insulin, homeostatic model of assessment index (HOMA-IR), lipids and highly sensitive C-reactive protein. CONCLUSIONS: 12 weeks of vitamin D3 supplementation in obese adolescents with 2,000 IU once daily resulted in a modest increase in 25(OH)D concentration in obese adolescents, but did not affect the lipid profile and markers of insulin resistance and inflammation. Further studies with higher doses of vitamin D3 and/or longer duration of supplementation are needed to understand if vitamin D3 supplementation can impact lipid profiles and markers of insulin resistance and inflammation in obese children.