title: Selenium status and associated factors in a British National Diet and Nutrition Survey: young people aged 4-18 y.
abstract: OBJECTIVE
  Assessment of selenium status to provide normative reference values, and investigation of associated socio-demographic factors, in a national sample of British young people aged 4-18 y.
  
  
  METHODS
  National Diet and Nutrition Survey-a nationwide cross-sectional sample of young people aged 4-18 y living in mainland Britain in 1997.
  
  
  METHODS
  Selenium status was measured, mainly in fasting blood samples, by plasma selenium concentration in 1127 participants, by red blood cell (RBC) selenium concentration in 1112, and by whole-blood glutathione peroxidase (GPx) activity in 658.
  
  
  RESULTS
  No evidence of severe selenium deficiency or toxicity was observed. Plasma selenium concentration was directly correlated with RBC selenium concentration, and both were associated directly, although less strongly, with GPx activity. Plasma and RBC selenium concentrations increased significantly with age, with RBC concentrations significantly higher in older girls than boys. Region of domicile exhibited a significant relationship. Associations also occurred with parental occupational social class, selenium concentrations being higher in more socially advantaged children. Black and Indian children had considerably higher concentrations than Caucasian children. Concentrations, especially of plasma selenium, were significantly lower in children either (or both) of whose parents were smokers, although, unexpectedly, there was no evidence that children who themselves smoked had lower levels.
  
  
  CONCLUSIONS
  The observed associations between selenium status indices and age, gender, social class, parental smoking and ethnic group indicate a complex network of biological factors which determine selenium concentrations in blood components, and which thus need to be controlled for when using these indices to assess selenium status in young people.
  
  
  BACKGROUND
  The survey was commissioned jointly by the Department of Health and the Ministry of Agriculture, Fisheries and Food, whose responsibility has since been transferred to the Food Standards Agency. Support for the further analysis presented in this paper was provided by the Department of Health.
authors.affiliation: MRC Human Nutrition Research, Elsie Widdowson Laboratory, Cambridge, UK. chris.bates@mrc-hnr.cam.ac.uk
authors.forename: C J
authors.initials: CJ
authors.lastname: Bates
authors.forename: C W
authors.initials: CW
authors.lastname: Thane
authors.forename: A
authors.initials: A
authors.lastname: Prentice
authors.forename: H T
authors.initials: HT
authors.lastname: Delves
authors.forename: J
authors.initials: J
authors.lastname: Gregory
mesh_terms: D000293:Adolescent; D000367:Age Factors; D000704:Analysis of Variance; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D004034:Diet Surveys; D005260:Female; D005979:Glutathione Peroxidase / Q000097:blood; D006801:Humans; D008297:Male; D009749:Nutrition Surveys; D012044:Regression Analysis; D012643:Selenium / Q000097:blood*; D012737:Sex Factors; D012907:Smoking / Q000097:blood; D012923:Social Class; D006113:United Kingdom
chemical_list: D005979:Glutathione Peroxidase; D012643:Selenium