title: Seasonal changes in vitamin D status among Danish adolescent girls and elderly women: the influence of sun exposure and vitamin D intake.
abstract: OBJECTIVE
  To determine seasonal variation in vitamin D status in healthy Caucasian adolescent girls and elderly community-dwelling women living in Denmark, and to quantify the impact of sun exposure and intake on the seasonal changes in vitamin D status.
  
  
  METHODS
  A 1-year longitudinal observational study of 54 girls (11-13 years) and 52 women (70-75 years). The participants were examined three times (winter-summer-winter). Serum 25-hydroxyvitamin D (S-25OHD) concentration and vitamin D intake were measured at each visit. Sun exposure was measured during summer.
  
  
  RESULTS
  S-25OHD concentrations (winter, summer, winter) were median (25, 75 percentiles) 23.4 (16.5, 36.4), 60.3 (42.7, 67.7), 29.5 (22.2, 40.4) and 47.2 (27.3, 61.1), 67.3 (35.1, 79.2), 50.5 (32.7, 65.5)nmol/l for girls and women, respectively. The usual sun habits were determinant (P=0.002) for change in vitamin D status from winter to summer. Vitamin D intake from supplements (P<0.0001) and diet (P=0.002) were determinants for change in vitamin D status from summer to winter. Winter vitamin D status of 50 nmol/l is achievable when vitamin D status the previous summer was ≈ 100 nmol/l. If summer vitamin D status is only ≈ 60 nmol/l, vitamin D status the following winter would be ≈ 28 nmol/l.
  
  
  CONCLUSIONS
  Low vitamin D status among adolescent girls and elderly women during two consecutive winter seasons, improved vitamin D status during the summer and better vitamin D status in women than in girls was found. The estimations show that a summer S-25OHD concentration ≈ 100 nmol/l is needed to achieve a concentration of ≈ 50 nmol/l the following winter.
authors: Department of Nutrition, National Food Institute, Technical University of Denmark, Søborg, Denmark. rian@food.dtu.dk
authors: R
authors: R
authors: Andersen
authors: C
authors: C
authors: Brot
authors: J
authors: J
authors: Jakobsen
authors: H
authors: H
authors: Mejborn
authors: C
authors: C
authors: Mølgaard
authors: L T
authors: LT
authors: Skovgaard
authors: E
authors: E
authors: Trolle
authors: I
authors: I
authors: Tetens
authors: L
authors: L
authors: Ovesen
mesh_terms: D000293:Adolescent; D000368:Aged; D002648:Child; D003718:Denmark / Q000453:epidemiology; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D015596:Nutrition Assessment; D009752:Nutritional Status; D012621:Seasons; D013472:Sunlight; D011795:Surveys and Questionnaires; D014807:Vitamin D / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000453:epidemiology
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D