title: Vitamin D status and its determinants in adolescents from the Northern Ireland Young Hearts 2000 cohort.
abstract: Despite recent concerns about the high prevalence of sub-clinical vitamin D deficiency in adolescents, relatively few studies have investigated the underlying reasons. The objective of the present study was to investigate the prevalence and predictors of vitamin D inadequacy among a large representative sample of adolescents living in Northern Ireland (54-55 degrees N). Serum concentrations of 25-hydroxyvitamin D (25(OH)D) were analysed by enzyme-immunoassay in a subgroup of 1015 of the Northern Ireland Young Hearts 2000 cohort; a cross-sectional study of 12 and 15 year-old boys and girls. Overall mean 25(OH)D concentration throughout the year was 64.3 (range 5-174) nmol/l; 56.7 and 78.1 nmol/l during winter and summer, respectively. Reported intakes of vitamin D were very low (median 1.7 microg/d). Of those adolescents studied, 3 % and 36 % were vitamin D deficient and inadequate respectively, as defined by serum 25(OH)D concentrations < 25 and < 50 nmol/l. Of the subjects, 46 % and 17 % had vitamin D inadequacy during winter and summer respectively. Gender differences were also evident with 38 % and 55 % of boys and girls respectively classified as vitamin D inadequate during winter (P < 0.001). Predictors of vitamin D inadequacy during winter were vitamin D intake and gender. In conclusion, there is a high prevalence of vitamin D inadequacy in white-skinned adolescents in Northern Ireland, particularly during wintertime and most evident in girls. There is a clear need for dietary recommendations for vitamin D in this age group and for creative strategies to increase overall vitamin D status in the population.
authors.affiliation: Department of Food and Nutritional Sciences, University College, Cork, Republic of Ireland, UK.
authors.forename: Tom R
authors.initials: TR
authors.lastname: Hill
authors.forename: Alice A
authors.initials: AA
authors.lastname: Cotter
authors.forename: Sarah
authors.initials: S
authors.lastname: Mitchell
authors.forename: Colin A
authors.initials: CA
authors.lastname: Boreham
authors.forename: Werner
authors.initials: W
authors.lastname: Dubitzky
authors.forename: Liam
authors.initials: L
authors.lastname: Murray
authors.forename: J J
authors.initials: JJ
authors.lastname: Strain
authors.forename: Albert
authors.initials: A
authors.lastname: Flynn
authors.forename: Paula J
authors.initials: PJ
authors.lastname: Robson
authors.forename: Julie M W
authors.initials: JM
authors.lastname: Wallace
authors.forename: Mairead
authors.initials: M
authors.lastname: Kiely
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Cashman
mesh_terms: D000293:Adolescent; D017195:Adolescent Nutritional Physiological Phenomena; D002136:Calcium, Dietary / Q000008:administration & dosage; D002648:Child; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D008297:Male; D009660:Northern Ireland / Q000453:epidemiology; D012621:Seasons; D012737:Sex Factors; D014807:Vitamin D / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000453:epidemiology* / Q000209:etiology
chemical_list: D002136:Calcium, Dietary; D014807:Vitamin D; C104450:25-hydroxyvitamin D