Vitamin D status of women in the Geelong Osteoporosis Study : association with diet and casual exposure to sunlight

Pasco, Julie A., Henry, Margaret J., Nicholson, Geoff C., Sanders, Kerrie M. and Kotowicz, Mark A. 2001, Vitamin D status of women in the Geelong Osteoporosis Study : association with diet and casual exposure to sunlight, Medical journal of Australia, vol. 175, no. 8, pp. 401-405.


Title Vitamin D status of women in the Geelong Osteoporosis Study : association with diet and casual exposure to sunlight
Author(s) Pasco, Julie A.
Henry, Margaret J.
Nicholson, Geoff C.
Sanders, Kerrie M.
Kotowicz, Mark A.
Journal name Medical journal of Australia
Volume number 175
Issue number 8
Start page 401
End page 405
Total pages 5
Publisher Australasian Medical Publishing Company
Place of publication Sydney, N.S.W.
Publication date 2001-10-15
ISSN 0025-729X
1326-5377
Keyword(s) 25 hydroxyvitamin D
vitamin D
Summary Objective: To assess vitamin D intake and casual exposure to sunshine in relation to serum 25-hydroxyvitamin D (25OHD) levels.

Design:
Cross-sectional study of a population-based, random sample of women aged 20-92 years, assessed between 1994 and 1997.

Setting and participants:
861 women from the Barwon Statistical Division (population, 218 000), which includes the city of Geelong (latitude 38° south) in Victoria.

Main outcome measures:
Vitamin D intake; serum 25OHD level; season of assessment; exposure to sunshine.

Results:
Median intake of vitamin D was 1.2 μg/day (range, 0.0-11.4 μg/day). Vitamin D supplements, taken by 7.9% of participants, increased intake by 8.1% to 1.3 μg/day (range, 0.0-101.2 μg/day) (P < 0.001). A dose-response relationship in serum 25OHD levels was observed for sunbathing frequency before and after adjusting for age (P < 0.05). During winter (May-October), serum 25OHD levels were dependent on vitamin D intake (partial r2 = 0.01; P < 0.05) and were lower than during summer (November-April) (age-adjusted mean, 59 nmol/L [95% CI, 57-62] v 81 nmol/L [95% CI, 78-84]; P < 0.05). No association was detected between serum 25OHD and vitamin D intake during summer. The prevalences of low concentrations of serum 25OHD were, for <28 nmol/L, 7.2% and 11.3% overall and in winter, respectively; and, for <50 nmol/L, 30.0% and 43.2% overall and in winter, respectively.

Conclusions:
At latitude 38° south, the contribution of vitamin D from dietary sources appears to be insignificant during summer. However, during winter vitamin D status is influenced by dietary intake. Australia has no recommended dietary intake (RDI) for vitamin D, in the belief that adequate vitamin D can be obtained from solar irradiation alone. Our results suggest that an RDI may be needed.
Language eng
Field of Research 119999 Medical and Health Sciences not elsewhere classified
Socio Economic Objective 970111 Expanding Knowledge in the Medical and Health Sciences
HERDC Research category C1.1 Refereed article in a scholarly journal
Copyright notice ©2001, Australasian Medical Publishing Company
Persistent URL http://hdl.handle.net/10536/DRO/DU:30042801

Document type: Journal Article
Collection: School of Medicine
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