title: Prevalence of vitamin D deficiency and its determinants in Australian adults aged 25 years and older: a national, population-based study.
abstract: OBJECTIVE
  Vitamin D deficiency is recognized as a global public health problem, but the population-based prevalence of deficiency and its determinants in Australian adults is not known. This study evaluated the vitamin D status of Australian adults aged ≥25 years and risk factors associated with vitamin D deficiency in this population.
  
  
  METHODS
  We studied a national sample of 11,247 Australian adults enrolled in the 1999/2000 Australian Diabetes, Obesity and Lifestyle (AusDiab) study drawn from 42 randomly selected districts throughout Australia.
  
  
  METHODS
  Serum concentrations of 25-hydroxyvitamin D [25(OH)D] were measured by immunoassay. Vitamin D deficiency was defined as a concentration <50 nmol/l. Information on demographic and lifestyle factors was derived from interview-administered questionnaires.
  
  
  RESULTS
  The mean serum 25(OH)D concentration was 63 nmol/l (95% CI: 59-67 nmol/l). Only 4% of the population had a level <25 nmol/l, but the prevalence of vitamin D deficiency (<50 nmol/l) was 31% (22% men; 39% women); 73% had levels <75 nmol/l. The prevalence of vitamin D deficiency increased significantly with age, was greater in women, in those of non-Europid origin, in the obese and those who were physically inactive and with a higher level of education. Deficiency was also more common during winter and in people residing in southern Australia (latitude >35°S); 42% of women and 27% of men were deficient during summer-autumn, which increased to 58% and 35%, respectively, during winter-spring.
  
  
  CONCLUSIONS
  Vitamin D deficiency is common in Australia affecting nearly one-third of adults aged ≥25 years. This indicates that strategies are needed at the population level to improve vitamin D status of Australians.
authors.affiliation: Centre for Physical Activity and Nutrition Research, School of Exercise and Nutrition Sciences, Deakin University, Melbourne, Australia. rmdaly@deakin.edu.au
authors.forename: Robin M
authors.initials: RM
authors.lastname: Daly
authors.forename: Claudia
authors.initials: C
authors.lastname: Gagnon
authors.forename: Zhong X
authors.initials: ZX
authors.lastname: Lu
authors.forename: Dianna J
authors.initials: DJ
authors.lastname: Magliano
authors.forename: David W
authors.initials: DW
authors.lastname: Dunstan
authors.forename: Ken A
authors.initials: KA
authors.lastname: Sikaris
authors.forename: Paul Z
authors.initials: PZ
authors.lastname: Zimmet
authors.forename: Peter R
authors.initials: PR
authors.lastname: Ebeling
authors.forename: Jonathan E
authors.initials: JE
authors.lastname: Shaw
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001315:Australia / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009313:National Health Programs / Q000706:statistics & numerical data; D009765:Obesity / Q000097:blood / Q000150:complications / Q000453:epidemiology; D011153:Population; D015995:Prevalence; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications / Q000453:epidemiology*
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D