title: Supplementation with 1000 IU vitamin D/d leads to parathyroid hormone suppression, but not increased fractional calcium absorption, in 4-8-y-old children: a double-blind randomized controlled trial.
abstract: BACKGROUND
  The effects of vitamin D supplementation in healthy prepubertal children on physiologic outcomes have not been investigated.
  
  
  OBJECTIVE
  The objective was to evaluate the effects of supplementation with 1000 IU vitamin D(3)/d on calcium absorption.
  
  
  METHODS
  In a double-blind, placebo-controlled trial, we randomly assigned 64 children to 1000 IU vitamin D(3)/d (n = 32) or placebo (n = 32) for 8 wk. Stable isotopes were used to assess calcium absorption. The main outcome measure was calcium absorption before and after supplementation.
  
  
  RESULTS
  All of the data are shown as means ± SDs. At baseline, vitamin D intake was 221 ± 79 IU/d and calcium intake was 830 ± 197 mg/d. Baseline serum 25-hydroxyvitamin D [25(OH)D] was not significantly correlated with fractional or total calcium absorption. After 8 wk, with baseline values used as a covariate, no differences were seen in fractional or total calcium absorption based on supplementation group (P = 0.75 and 0.36, respectively). Supplemented children had a significant increase in 25(OH)D concentrations (from 27.7 ± 7.4 to 36.0 ± 10.3 ng/mL; P < 0.0001) and a decrease in parathyroid hormone (from 21.4 ± 10.4 to 12.9 ± 7.1 pg/mL; P < 0.001); no significant changes in the placebo group were observed. No adverse side effects were noted in either group.
  
  
  CONCLUSIONS
  Vitamin D(3) supplementation at 1000 IU/d increases 25(OH)D and decreases parathyroid hormone in children with average vitamin D intakes below the dietary recommendations of the Institute of Medicine. However, no significant effects of this change on calcium absorption occurred. This trial was registered at clinicaltrials.gov as NCT 00868738.
authors.affiliation: USDA/Agricultural Research Service, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA. sabrams@bcm.edu
authors.forename: Steven A
authors.initials: SA
authors.lastname: Abrams
authors.forename: Keli M
authors.initials: KM
authors.lastname: Hawthorne
authors.forename: Zhensheng
authors.initials: Z
authors.lastname: Chen
mesh_terms: D000042:Absorption; D002136:Calcium, Dietary / Q000008:administration & dosage / Q000493:pharmacokinetics*; D002648:Child; D002675:Child, Preschool; D002762:Cholecalciferol / Q000008:administration & dosage* / Q000493:pharmacokinetics; D004032:Diet; D019587:Dietary Supplements; D004311:Double-Blind Method; D005006:Ethnicity; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D016014:Linear Models; D008297:Male; D010281:Parathyroid Hormone / Q000037:antagonists & inhibitors*; D016896:Treatment Outcome; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood
chemical_list: D002136:Calcium, Dietary; D010281:Parathyroid Hormone; D014807:Vitamin D; D002762:Cholecalciferol; C097949:1,25-dihydroxyvitamin D; C104450:25-hydroxyvitamin D