title: Factors influencing the vitamin D status of 10-year-old urban South African children.
abstract: OBJECTIVE
  Assessment of vitamin D status in a cohort of healthy 10-year-old urban children and the factors that influence vitamin D status in these children.
  
  
  METHODS
  A cross-sectional study. Blood samples were collected across four seasons of the year for the biochemical determination of serum 25-hydroxyvitamin D [25(OH)D]. Anthropometric measurements (height and weight), BMI and total fat and lean mass (determined by the dual energy X-ray absorptiometry) were measured. 25(OH)D concentrations were assessed by chemiluminescent assay.
  
  
  METHODS
  Study of children in the Greater Johannesburg area of South Africa who form the Bone Health sub-cohort of the longitudinal Birth to Twenty cohort.
  
  
  METHODS
  Three hundred and eighty-five children who form the Bone Health sub-cohort of the longitudinal Birth to Twenty cohort.
  
  
  RESULTS
  White children had significantly higher 25(OH)D than their black peers (120·0 (sd 36·6) nmol/l v. 93·3 (sd 34·0) nmol/l, respectively). Seasonal variations in 25(OH)D levels were found only in white children, with 25(OH)D levels being significantly higher in white than in black children during the autumn and summer months. In multiple regression analysis, season, ethnicity, sex and total fat mass were the factors found to have an influence on 25(OH)D. Vitamin D deficiency (7 %) and insufficiency (19 %) were uncommon among the 10-year-old children.
  
  
  CONCLUSIONS
  Vitamin D supplementation or fortification is not warranted in healthy children living in Johannesburg. However, further studies need to confirm this in other regions of the country, especially in those living further south and with less sunshine during the winter months.
authors.affiliation: MRC Mineral Metabolism Research Unit & Birth to Twenty Research Programme, Department of Paediatrics and Child Health, Chris Hani Baragwanath Hospital, The University of the Witwatersrand, PO Bertsham, 2013 Johannesburg, South Africa. machuene.poopedi@wits.ac.za
authors.forename: Machuene A
authors.initials: MA
authors.lastname: Poopedi
authors.forename: Shane A
authors.initials: SA
authors.lastname: Norris
authors.forename: John M
authors.initials: JM
authors.lastname: Pettifor
mesh_terms: D044383:Black People; D001823:Body Composition; D015992:Body Mass Index; D050071:Bone Density Conservation Agents / Q000008:administration & dosage / Q000097:blood; D002648:Child; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D009752:Nutritional Status; D012621:Seasons; D012880:Skin Pigmentation; D013019:South Africa; D013472:Sunlight; D014807:Vitamin D / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000097:blood*; D014808:Vitamin D Deficiency / Q000097:blood / Q000453:epidemiology / Q000208:ethnology; D044465:White People
chemical_list: D050071:Bone Density Conservation Agents; D014807:Vitamin D; C104450:25-hydroxyvitamin D