title: Widespread vitamin D deficiency among adults from northern Poland (54°N) after months of low and high natural UVB radiation.
abstract: BACKGROUND
  Widespread vitamin D deficiency has been reported worldwide and evidence of its deleterious effects on health has been accumulating. There is insufficient data concerning vitamin D status among the Polish adult population. The aim of the study was to determine vitamin D status and factors influencing it - UVB exposure, supplementation, and diet - among adults in northern Poland following months of low and high natural UVB radiation.
  
  
  METHODS
  Adults were recruited in an outpatient clinic. All were examined twice in 2012: in winter (in February, March and the first half of April), and autumn (between 25 September and 8 November). Questionnaire examinations were performed, and serum concentrations of 25-hydroxy-vitamin D (25(OH)D), calcium, phosphorus, parathyroid hormone (PTH), and alkaline phosphatase (ALP) were determined.
  
  
  RESULTS
  40 men and 69 women participated in the study (age 48.4 ± 15 years, body mass index (BMI) 25.9 ± 4.3 kg/m2, mean ± SD). Mean 25(OH)D serum level in winter was 13.3 ± 6.6 ng/mL, 81.1% of participants were vitamin D-deficient. Mean 25(OH)D concentration in autumn was 22.8 ± 7.9 ng/mL (42.2% of subjects were vitamin D-deficient). Median 25(OH)D and PTH concentrations between the two examination periods differed significantly (11.9 vs. 22.1 ng/mL, and 46.3 vs. 32.2 pg/mL, respectively). In autumn, negative correlations were found between: 25(OH)D and PTH serum levels, 25(OH)D and BMI values. When compared to respective counterparts, participants declaring vitamin D supplementation, and sunbed use had significantly higher median 25(OH)D concentrations.
  
  
  CONCLUSIONS
  UV exposure during the summer was insufficient to provide adequate vitamin D status for almost half of the participants by as soon as the early autumn. Our results suggest all-year-round vitamin D supplementation should be widely implemented.
authors.affiliation: Department of Endocrinology and Internal Medicine, Medical University of Gdansk, Poland. piotrkmiec@gumed.edu.pl.
authors.forename: Piotr
authors.initials: P
authors.lastname: Kmieć
authors.forename: Michał
authors.initials: M
authors.lastname: Żmijewski
authors.forename: Maria
authors.initials: M
authors.lastname: Lizakowska-Kmieć
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Sworczak
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011044:Poland / Q000453:epidemiology; D040242:Risk Reduction Behavior; D012621:Seasons; D055108:Sunbathing / Q000706:statistics & numerical data; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood* / Q000175:diagnosis* / Q000453:epidemiology; D044465:White People / Q000706:statistics & numerical data
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D