Vitamin D and Vascular Health in Children

Inclusion Criteria:

• Eligible subjects will be 10 to 18 years of age;
• obese or overweight (BMI ≥85th %tile);
• otherwise healthy, and
• have a serum 25(OH)D concentration <20 ng/mL

Children taking multivitamins should be able to hold off their multivitamins during the course of the study.

Exclusion Criteria:

Children will be excluded if they

• (a) have hepatic or renal disease, metabolic rickets, malabsorptive disorders, primary hyperparathyroidism, hyperthyroidism, or other chronic disorders that could affect vitamin D metabolism;
• (b) are receiving treatment with anticonvulsants, systemic glucocorticoids, pharmacologic doses of vitamin D (≥1000 IU of vitamin D2 or D3 daily), antihypertensives, vasoactive drugs, antilipidemics, metformin, antipsychotics, or other oral insulin regulators;
• (c) have cholelithiasis or urolithiasis;
• (d) have type 1 or type 2 diabetes; or
• (e) have a condition or underlying abnormality that could compromise the safety of the subject.

Post-menarchial girls with a positive pregnancy test at randomization, or subjects found during the screening phase to have hypercalcemia (serum calcium >10.8 mg/dL) or significant fasting hyperglycemia (fasting blood glucose ≥ 125 mg/dL) will also be excluded.