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Vitamin D insufficiency in South-East Queensland

Authors:
1
McGrath JJ, Kimlin M, Saha S, Eyles D, Parisi A. (2001) Vitamin D insufficiency
in south-east Queensland. Medical Journal of Australia. 174; 150-151.
Vitamin D insufficiency in south-east Queensland
Associate Professor John J. McGrath MBBS, PhD
Director, Queensland Centre for Schizophrenia Research
And Department of Psychiatry, University of Queensland
Mr. Michael G. Kimlin BAppSc, MAppSc
Associate Lecturer, Physics
Centre for Astronomy and Atmospheric Research
Department of Biological and Physical Sciences
Faculty of Sciences
University of Southern Queensland
Mr. Sukanta Saha MSc, MCN
Scientist – Epidemiology Stream
Queensland Centre for Schizophrenia Research
Dr. Darryl W. Eyles BSc, PhD
Scientist – Biomedical Stream
Queensland Centre for Schizophrenia Research
Dr. Alfio V. Parisi PhD, MAppSc
Senior Lecturer
Centre for Astronomy and Atmospheric Research
Department of Biological and Physical Sciences
Faculty of Sciences
University of Southern Queensland
Address for correspondence:
Associate Professor John McGrath
Queensland Centre for Schizophrenia Research
Wolston Park Hospital
Wacol, Queensland, 4076
Australia
Ph +61 7 3271 8595
Fax +61 7 3271 8567
E-mail jjm@brain.wph.uq.edu.au
2
Studies from Perth
1
, Hobart
2
, central Victoria
3
, and Adelaide
4
have recently
drawn attention to the surprisingly high rates of vitamin D insufficiency and
deficiency in Australia (often defined as 50nmol/L and 38nmol/L 25
hydroxyvitamin D
3
respectively). There has been a lack of data from subtropical
regions such as Queensland, where there is more intense ultraviolet radiation.
Our group has an interest in vitamin D
5
, and had the opportunity to examine
vitamin D levels in a case-control study designed to examine risk factors for
psychosis.
Within an area of south-east Queensland (latitude 27
0
south), we randomly
sampled individuals with psychosis from a wide range of sites. A well control
group was drawn from the same catchment area. Ultraviolet radiation levels
were measured using a permanently mounted outdoor erythemal UV meter and
sunshine duration was measured with a Campbell-Stokes recorder. Serum 25
hydroxyvitamin D
3
levels were measured with a commercially available radio-
immunoassay (DiaSorin Inc). All subjects gave written, informed consent, and
the study was approved by the local Institutional Ethics Committee.
The sample consisted of 222 males and 192 females. The mean age was 42.0
years (SD 13.2). 113 subjects lived in “rural areas” as defined by the Australian
Bureau of Statistics. Overall the mean (and standard deviation; range) for 25
hydroxyvitamin D
3
in this sample was 69.1 nmol/L (26.2; 12.2-174.5). 23.4% of
the sample had levels equal or less than 50 nmol/L, and 8% of the sample had
levels equal or less than 38 nmol/L. There was no significant group difference in
vitamin D levels between the subjects with psychosis and the well controls
(t=0.026, df=412, p = 0.98). Males had significantly higher 25 hydroxyvitamin D
3
levels compared to females (mean, SD; 72.0, 25.8: 65.9, 26.4 nmol/L
respectively: t=2.36, df =412, p=0.02). Those living in rural areas had significantly
higher 25 hydroxyvitamin D
3
levels compared to those living in urban areas
(mean, SD: 74.0, 31.6; 68.1, 23.5 nmol/L respectively: t = 2.00, df=371, p = 0.04).
3
There was no significant correlation between age and 25 hydroxyvitamin D
3
level
(Pearson r= -0.06, p=0.25). There were statistically significant positive
correlations between 25 hydroxyvitamin D
3
and both sunshine (r=0.10, p=0.04)
and ultraviolet radiation (r=0.24, p=0.001). When examined by quartiles of
sunshine duration (1
st
quartile being the shortest and 4
th
quartile being the
longest duration of sunshine), the mean (SD) 25 hydroxyvitamin D
3
levels for the
1
st
, 2
nd
, 3
rd
and 4
th
quartiles were not strictly linear - 64.3 (24.9), 66.1 (23.1), 76.3
(24.8) and 67.0 (31.5) respectively.
The within-month variation shown in the Figure was least for July, which also had
the lowest mean 25 hydroxyvitamin D
3
levels. We speculate that behaviour
during this time of year was modified (less outdoor activity, less skin exposures
etc) and/or the weaker ultraviolet radiation during this month was less efficient in
producing vitamin D. Living in a subtropical climate does not guarantee
adequate vitamin D and supplementation with vitamin D may be more widely
needed than previously thought in Queensland.
References
1. Vasikaran SD, Sturdy G, Musk AA, Flicker L. Vitamin D insufficiency and
hyperparathyroidism in Perth blood donors. Med J Australia 2000 ;172: 406-7.
2. Jones G, Blizzard CL, Riley MD, Paramaeswaran V, Greenway TM, Dwyer T.
Vitamin D levels in prepubertal children in Southern Tasmania: prevalence
and determinants. Eur J Clin Nutr 1999 ;52: 824-9.
3. Marks R, Foley PA, Jolley D, Knight KR, Harrison J, Thompson SC. The
effect of regular sunscreen use on vitamin D levels in an Australian
population. Results of a randomized controlled trial [see comments].
Arch.Dermatol. 1995 ;131: 415-21.
4. Need AG, Morris HA, Horowitz M, Nordin BEC. Effects of skin thickness, age,
body fat, and sunlight on serum 25-hydroxyvitamin D. Amer J Clin Nutr 1993
;58: 882-5.
5. McGrath J. Hypothesis: is low prenatal vitamin D a risk-modifying factor for
schizophrenia? Schizophr.Res. 1999 ;40: 173-7.
4
Figure 1
(a) Upper panel. Mean monthly erythemal ultraviolet radiation (joules per square
metre) and mean monthly duration of sunshine (hours).
(b) Lower panel. Boxplot of 25 hydroxyvitamin D levels per month (nmol/L). The
centre line in the box is the mean, while the upper and low borders of the box
define the 25
th
and 75
th
percentile. The whiskers indicate minimum and
maximum values excluding outliers, asterisks indicate outliers.
Duration of Sunshine (Hours)
Erythemal Ultraviolet Radiation (Joules/metre
2
)
25 Hydroxyvitamin D
3
(nmol/L)
... The prevalence of vitamin D deficiency among females in Saudi Arabia is also very high, ranging from 30% to 80% (El-Hajj et al., 2001). Regions with a higher prevalence of vitamin D deficiency can be supported through appropriate patient education, health promotion, and health awareness programs conducted by community pharmacies (McGrath et al., 2001). The use of vitamin D and other dietary supplements has surged in many developed countries in recent years (Tran et al., 2013). ...
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