The high prevalence of vitamin D insufficiency across Australian populations is only partly explained by season and latitude

Ingrid A.F. van der Mei*, Anne Louise Ponsonby, Ola Engelsen, Julie A. Pasco, John J. McGrath, Daryl W. Eyles, Leigh Blizzard, Terence Dwyer, Robyn Lucas, Graeme Jones

*Corresponding author for this work

    Research output: Contribution to journalReview articlepeer-review

    208 Citations (Scopus)

    Abstract

    Background: Inadequate sun exposure and dietary vitamin D intake can result in vitamin D insufficiency. However, limited data are available on actual vitamin D status and predictors in healthy individuals in different regions and by season. Methods: We compared vitamin D status [25-hydroxyvitamin D; 25(OH)D] in people < 60 years of age using data from cross-sectional studies of three regions across Australia: southeast Queensland (27°S; 167 females and 211 males), Geelong region (38°S; 561 females), and Tasmania (43°S; 432 females and 298 males). Results: The prevalence of vitamin D insufficiency (≤ 50 nmol/L) in women in winter/spring was 40.5% in southeast Queensland, 37.4% in the Geelong region, and 67.3% in Tasmania. Season, simulated maximum daily duration of vitamin D synthesis, and vitamin D effective daily dose each explained around 14% of the variation in 25(OH)D. Although latitude explained only 3.9% of the variation, a decrease in average 25(OH)D of 1.0 (95% confidence interval, 0.7-1.3) nmol/L for every degree increase in latitude may be clinically relevant. In some months, we found a high insufficiency or even deficiency when sun exposure protection would be recommended on the basis of the simulated ultraviolet index. Conclusion: Vitamin D insufficiency is common over a wide latitude range in Australia. Season appears to be more important than latitude, but both accounted for less than one-fifth of the variation in serum 25(OH)D levels, highlighting the importance of behavioral factors. Current sun exposure guidelines do not seem to fully-prevent vitamin D insufficiency, and consideration should be given to their modification or to pursuing other means to achieve vitamin D adequacy.

    Original languageEnglish
    Pages (from-to)1132-1139
    Number of pages8
    JournalEnvironmental Health Perspectives
    Volume115
    Issue number8
    DOIs
    Publication statusPublished - Aug 2007

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