title: Vitamin D is a major determinant of bone mineral density at school age.
abstract: BACKGROUND
  Vitamin D insufficiency in children may have long-term skeletal consequences as vitamin D affects calcium absorption, bone mineralization and bone mass attainment.
  
  
  RESULTS
  This school-based study investigated vitamin D status and its association with vitamin D intake and bone health in 195 Finnish children and adolescents (age range 7-19 years). Clinical characteristics, physical activity and dietary vitamin D intake were evaluated. Blood and urine samples were collected for serum 25-hydroxyvitamin D (25-OHD) and other parameters of calcium homeostasis. Bone mineral density (BMD) and body composition were measured with dual-energy X-ray absorptiometry (DXA). Altogether 71% of the subjects were vitamin D insufficient (25-OHD <50 nmol/L). The median 25-OHD was 41 nmol/L for girls and 45 nmol/L for boys, and the respective median vitamin D intakes 9.1 µg/day and 10 µg/day. In regression analysis, after adjusting for relevant factors, 25-OHD concentration explained 5.6% of the variance in lumbar BMD; 25-OHD and exercise together explained 7.6% of the variance in total hip BMD and 17% of the variance in whole body BMD. S-25-OHD was an independent determinant of lumbar spine and whole body BMD and in magnitude surpassed the effects of physical activity.
  
  
  CONCLUSIONS
  Vitamin D insufficiency was common even when vitamin D intake exceeded the recommended daily intake. Vitamin D status was a key determinant of BMD. The findings suggest urgent need to increase vitamin D intake to optimize bone health in children.
authors: Folkhälsan Institute of Genetics, University of Helsinki, Helsinki, Finland. minna.pekkinen@helsinki.fi
authors: Minna
authors: M
authors: Pekkinen
authors: Heli
authors: H
authors: Viljakainen
authors: Elisa
authors: E
authors: Saarnio
authors: Christel
authors: C
authors: Lamberg-Allardt
authors: Outi
authors: O
authors: Mäkitie
mesh_terms: D015502:Absorptiometry, Photon; D000293:Adolescent; D000328:Adult; D015519:Bone Density; D002118:Calcium / Q000378:metabolism; D002648:Child; D005260:Female; D005387:Finland; D006801:Humans; D008297:Male; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood / Q000652:urine; D014808:Vitamin D Deficiency / Q000097:blood* / Q000652:urine*
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D; D002118:Calcium