Efficacy of Vitamin D Supplementation in Obese Children

Vitamin D deficiency is common in the general population in the United States, but is more common in overweight and obese children. Additionally, vitamin D levels are inversely correlated with body mass index, hypertension, inflammatory markers and insulin resistance. There are currently no clear guidelines regarding vitamin D replacement in obese but otherwise healthy children. The Endocrine Society recommends that children with vitamin D deficiency should take 2000 IU once a day for at least 6 weeks; however, they state that obese children may need 2-3 times this dose in order to reach sufficient levels. The goals of this study are: 1. To determine the prevalence of vitamin D sufficiency (\>30 ng/mL), insufficiency (21-29 ng/mL); deficiency (10-19 ng/mL) and severe vitamin D deficiency (\<10 ng/dL) in an obese pediatric population (2-11 years) as measured by 25-hydroxyvitamin D. 2. To determine if vitamin D level correlates with percentage body fat by bioelectrical impedance analysis and/or visceral fat by waist circumference in children ages 5 - 11 years. 3. To observe the effect of vitamin D replacement in obese children with vitamin D deficiency using two different replacement dosage levels recommended by the Endocrine Society over three months: 2000 IU once a day (general pediatric dose) vs 6000 IU once a day (suggested obesity dose) in children between the ages of 5 - 11 years. 4. To measure vitamin D levels, bone markers, inflammatory markers and vitamin D binding protein before and after vitamin D supplementation in children between the ages of 5 - 11 years. Analysis will be stratified by degree of obesity (Class I, Class II, Class III) and season.