British Journal of Nutrition

Full Papers

Vitamin D status and its determinants in adolescents from the Northern Ireland Young Hearts 2000 cohort

Tom R. Hilla1, Alice A. Cottera1, Sarah Mitchella1, Colin A. Borehama3, Werner Dubitzkya4, Liam Murraya6, J. J. Straina5, Albert Flynna1, Paula J. Robsona5, Julie M. W. Wallacea5, Mairead Kielya1 and Kevin D. Cashmana1a2 c1

a1 Department of Food and Nutritional Sciences, University College, Cork, Republic of Ireland

a2 Department of Medicine, University College, Cork, Republic of Ireland

a3 UCD Institute for Sport and Health, University College, Dublin, Republic of Ireland

a4 Systems Biology Research Group, University of Ulster, Coleraine, UK

a5 Northern Ireland Centre for Food and Health, University of Ulster, Coleraine, UK

a6 Department of Epidemiology and Public Health, Queens University, Belfast, UK


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°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 μg/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.

(Received June 21 2007)

(Revised September 11 2007)

(Accepted September 13 2007)

(Online publication January 15 2008)


c1 Corresponding author: Professor Kevin D. Cashman, fax +353 21 4270244, email


Abbreviations: 25(OH)D, 25-hydroxyvitamin D; YH2000, Young Hearts 2000