title: A 16-week randomized clinical trial of 2000 international units daily vitamin D3 supplementation in black youth: 25-hydroxyvitamin D, adiposity, and arterial stiffness.
abstract: BACKGROUND
  Vitamin D insufficiency/deficiency is commonly observed in black youth.
  
  
  OBJECTIVE
  The aim was to determine 25-hydroxyvitamin D [25(OH)D] in response to 2000 IU vitamin D supplementation over time; to evaluate the relation between 25(OH)D concentrations and total body fat mass by dual-energy x-ray absorptiometry; and to determine whether vitamin D supplementation improves arterial stiffness measured by pulse wave velocity (PWV).
  
  
  METHODS
  We conducted a randomized, blinded, controlled clinical trial.
  
  
  METHODS
  Forty-nine normotensive black boys and girls, aged 16.3 ± 1.4 yr, were randomly assigned to either the control group (400 IU/d; n = 24) or the experimental group (2000 IU/d; n = 25).
  
  
  RESULTS
  Plasma 25(OH)D values at baseline and at 4, 8, and 16 wk were 34.0 ± 10.6, 44.9 ± 9.4, 51.2 ± 11.1, and 59.8 ± 18.2 nmol/liter, respectively, for the control group; and 33.1 ± 8.7, 55.0 ± 11.8, 70.9 ± 22.0, and 85.7 ± 30.1 nmol/liter, respectively, for the experimental group. The experimental group vs. the control group reached significantly higher 25(OH)D concentrations at 8 and 16 wk, respectively. Partial correlation analyses indicated that total body fat mass at baseline was significantly and inversely associated with 25(OH)D concentrations in response to the 2000-IU supplement across time. Furthermore, carotid-femoral PWV increased from baseline (5.38 ± 0.53 m/sec) to posttest (5.71 ± 0.75 m/sec) in the control group (P = 0.016), whereas in the experimental group carotid-femoral PWV decreased from baseline (5.41 ± 0.73 m/sec) to posttest (5.33 ± 0.79 m/sec) (P = 0.031).
  
  
  CONCLUSIONS
  Daily 2000 IU vitamin D supplementation may be effective in optimizing vitamin D status and counteracting the progression of aortic stiffness in black youth. Plasma 25(OH)D concentrations in response to the 2000 IU/d supplementation are negatively modulated by adiposity.
authors.affiliation: Georgia Prevention Institute, Department of Pediatrics, Medical College of Georgia, Augusta, Georgia 30912, USA. ydong@mail.mcg.edu
authors.forename: Yanbin
authors.initials: Y
authors.lastname: Dong
authors.forename: Inger S
authors.initials: IS
authors.lastname: Stallmann-Jorgensen
authors.forename: Norman K
authors.initials: NK
authors.lastname: Pollock
authors.forename: Ryan A
authors.initials: RA
authors.lastname: Harris
authors.forename: Daniel
authors.initials: D
authors.lastname: Keeton
authors.forename: Ying
authors.initials: Y
authors.lastname: Huang
authors.forename: Ke
authors.initials: K
authors.lastname: Li
authors.forename: Reda
authors.initials: R
authors.lastname: Bassali
authors.forename: De-huang
authors.initials: DH
authors.lastname: Guo
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Thomas
authors.forename: Gary L
authors.initials: GL
authors.lastname: Pierce
authors.forename: Jennifer
authors.initials: J
authors.lastname: White
authors.forename: Michael F
authors.initials: MF
authors.lastname: Holick
authors.forename: Haidong
authors.initials: H
authors.lastname: Zhu
mesh_terms: D050154:Adiposity / Q000187:drug effects* / Q000502:physiology; D000293:Adolescent; D001158:Arteries / Q000000981:diagnostic imaging / Q000187:drug effects / Q000473:pathology*; D044383:Black People / Q000706:statistics & numerical data; D002112:Calcifediol / Q000097:blood*; D002318:Cardiovascular Diseases / Q000097:blood / Q000000981:diagnostic imaging / Q000473:pathology / Q000517:prevention & control*; D002762:Cholecalciferol / Q000008:administration & dosage*; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D008297:Male; D016037:Single-Blind Method; D013997:Time Factors; D014463:Ultrasonography
chemical_list: D002762:Cholecalciferol; D002112:Calcifediol