title: A randomized clinical trial of vitamin D supplementation in healthy adolescents.
abstract: OBJECTIVE
  The most safe and effective dose of vitamin D supplementation for healthy adolescents is currently unknown. The aim of this study was to compare the efficacy of 200 IU versus 1,000 IU of daily vitamin D3 for supplementation in healthy adolescents with baseline vitamin D sufficiency.
  
  
  METHODS
  We conducted a double-blind, randomized clinical trial. Fifty-six subjects, ages 11-19 years, with baseline vitamin D sufficiency received 1,000 IU or 200 IU of daily vitamin D3 for 11 weeks. Compliance was assessed using MEMS6 Trackcaps and pill counts.
  
  
  RESULTS
  Fifty-three subjects completed the clinical trial. Subjects in the two treatment arms were similar in terms of age, race, gender, body mass index, and dietary calcium and vitamin D intake. Serum 25(OH)D level in the 200 IU treatment arm was 28.1 ± 6.2 ng/mL at baseline (mean ± SD) and 28.9 ± 7.0 ng/mL at follow-up. In the 1,000 IU treatment arm, 25(OH)D levels were 29.0 ± 7.3 and 30.1 ± 6.6 at baseline and follow-up, respectively. Mean change in 25(OH)D level did not differ significantly between treatment arms (p = .87), nor did mean change in parathyroid hormone, calcium, phosphate, bone turnover markers, fasting glucose, or fasting insulin.
  
  
  CONCLUSIONS
  In healthy adolescents with baseline vitamin D sufficiency, supplementation with vitamin D3 doses of 200 and 1,000 IU for 11 weeks did not increase serum 25(OH)D levels, with no significant difference observed between treatment arms.
authors.affiliation: Division of Endocrinology, Department of Medicine, Boston Children's Hospital, Boston, MA, USA. melissa.putman@childrens.harvard.edu
authors.forename: Melissa S
authors.initials: MS
authors.lastname: Putman
authors.forename: Sarah A B
authors.initials: SA
authors.lastname: Pitts
authors.forename: Carly E
authors.initials: CE
authors.lastname: Milliren
authors.forename: Henry A
authors.initials: HA
authors.lastname: Feldman
authors.forename: Kristina
authors.initials: K
authors.lastname: Reinold
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Gordon
mesh_terms: D000293:Adolescent; D001900:Boston; D002648:Child; D019587:Dietary Supplements; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D055118:Medication Adherence; D016896:Treatment Outcome; D014807:Vitamin D / Q000627:therapeutic use*; D014808:Vitamin D Deficiency / Q000188:drug therapy*; D055815:Young Adult
chemical_list: D014807:Vitamin D