title: Association of serum 25-hydroxyvitamin D₃ and D₂ with academic performance in childhood: findings from a prospective birth cohort.
abstract: BACKGROUND
  Higher total serum 25-hydroxyvitamin D (25(OH)D) concentrations have been associated with better cognitive function mainly in cross-sectional studies in adults. It is unknown if the associations of different forms of 25(OH)D (25(OH)D(3) and 25(OH)D(2)) are similar.
  
  
  METHODS
  Prospective cohort study (n=3171) with serum 25(OH)D(3) and 25(OH)D(2) concentrations measured at mean age of 9.8 years and academic performance at age 13-14 years (total scores in English, mathematics and science) and 15-16 years (performance in General Certificates of Education examinations).
  
  
  RESULTS
  Serum 25(OH)D(3) concentrations were not associated with any educational outcomes. Higher 25(OH)D(2) concentrations were associated with worse performance in English at age 13-14 years (adjusted SD change per doubling in 25(OH)D(2) (95% CI) -0.05 (-0.08 to -0.01)) and with worse academic performance at age 15-16 years (adjusted OR for obtaining ≥5 A*-C grades (95% CI) 0.91 (0.82 to 1.00)).
  
  
  CONCLUSIONS
  The null findings with 25(OH)D(3) are in line with two previous cross-sectional studies in children. It is possible that the positive association of 25(OH)D with cognitive function seen in adults does not emerge until later in life or that the results from previous cross-sectional adult studies are due to reverse causality. The unexpected inverse association of 25(OH)D(2) with academic performance requires replication in further studies. Taken together, our findings do not support suggestions that children should have controlled exposure to sunlight, or vitamin D supplements, in order to increase academic performance.
authors.affiliation: MRC Centre for Causal Analysis in Translational Epidemiology, School of Social and Community Medicine, University of Bristol, Oakfield House, 15-23 Oakfield Grove, Clifton, Bristol BS8 2BN, UK. anna-maija.tolppanen@uef.fi
authors.forename: Anna-Maija
authors.initials: AM
authors.lastname: Tolppanen
authors.forename: Adrian
authors.initials: A
authors.lastname: Sayers
authors.forename: William D
authors.initials: WD
authors.lastname: Fraser
authors.forename: Debbie A
authors.initials: DA
authors.lastname: Lawlor
mesh_terms: D015652:25-Hydroxyvitamin D 2 / Q000097:blood*; D000293:Adolescent; D000367:Age Factors; D002112:Calcifediol / Q000008:administration & dosage / Q000097:blood*; D002118:Calcium / Q000097:blood; D002648:Child; D002851:Chromatography, High Pressure Liquid; D004521:Educational Measurement; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D010281:Parathyroid Hormone / Q000097:blood; D011446:Prospective Studies; D012709:Serum Albumin; D012737:Sex Factors; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires; D053719:Tandem Mass Spectrometry; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014815:Vitamins / Q000097:blood
chemical_list: D010281:Parathyroid Hormone; D012709:Serum Albumin; D014815:Vitamins; D014807:Vitamin D; D015652:25-Hydroxyvitamin D 2; C104450:25-hydroxyvitamin D; D002112:Calcifediol; D002118:Calcium