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Selenium, zinc and copper status in Tasmania : dietary, lifestyle and some genetic associations

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Beckett, JM (2010) Selenium, zinc and copper status in Tasmania : dietary, lifestyle and some genetic associations. PhD thesis, University of Tasmania.

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Abstract

Micronutrient deficiency is a public health problem thought to affect a third of the
world's population. In Tasmania, selenium deficiency occurred in livestock, and it has
been hypothesised that the human population may be at risk of inadequate intakes.
There are few Australian studies of trace element status, and previous studies in
Tasmania have been very limited and have provided conflicting results.
The primary aim of this thesis was:
• To assess the selenium status of people in northern Tasmania;
• To identify factors that may influence selenium status in these people;
• To determine groups in this population that may be at increased risk of low
selenium status.
A secondary aim was to conduct an opportunistic study to assess the copper and zinc
status in the same population, and determine some of the factors which may be
associated with copper and zinc status in this population.
The main study was a cross sectional population study of approximately 500 subjects
randomly selected from the electoral roll in the northern Tasmania; this was
preceeded by a preliminary study which used a convenience sample from this same
geographical region, and some technical work on the assessment of copper and zinc
status.
Indices of trace element status measured included dietary intake, serum levels and
functional markers of status, such as glutathione peroxidase activity for selenium
status. This was linked with data on lifestyle habits, anthropometric measurements, dietary analysis for other nutrients, and the measurement of total antioxidant status
and lipid profiles.
Results from the preliminary research (n = 198) suggested that marginal selenium
status may be reasonably widespread in this population, and that certain gender/age
groups may also consume inadequate zinc. Hereditary haemochromatosis was not
observed to have a major effect on trace element status.
The population study on 498 subjects from the electoral rolls of north, north west and
north eastern Tasmania, suggested a high prevalence of marginal selenium status.
Northern Tasmanians had mean selenium intakes of 77.4 and 65.1 ug/d for men and
women respectively; with 27% of all subjects consuming inadequate amounts of
selenium as indicated by NH&MRC guidelines on dietary intakes.
Mean serum selenium was 1.13 umol/L; and hence a large proportion of the
population (80%) was estimated to have serum selenium concentrations below
threshold levels associated with selenoprotein requirements. The majority of subjects
also had serum selenium concentrations below the level suggested to offer
chemopreventative benefits for some cancers. Associations with a common
selenoprotein SNP were not found.
In investigations of zinc status, men in particular appeared at risk of inadequacy. Zinc
intakes were 12.6 and 10.9 mg/d for men and women respectively. Fifty two percent
of men consumed inadequate zinc compared to only 9% of women. Mean serum zinc
concentration was 13.0 umol/L and when compared to the WHO cut-off, 15% of all
men had low serum zinc; the prevalence of which rose in older age ranges.
Investigations of copper status suggested that copper deficiency was unlikely in this
population. Mean serum copper concentrations were 15.5 and 18.9 umol/L for men
and women respectively; well above the lower clinical reference range.
These findings indicate that many Tasmanians may have marginal selenium status, and
that particular population sub-groups may additionally be susceptible to inadequate zinc
status. Further research is required. However, with our increasing understanding of the
importance of these essential trace elements in maintaining health and for reducing
susceptibility to some chronic diseases, the findings are important. There is potential, to
be tested, that increased intakes could possibly benefit an aging Tasmanian population,
which leads the country in chronic disease rates.

Item Type: Thesis (PhD)
Keywords: Trace elements, Selenium in human nutrition
Copyright Holders: The Author
Copyright Information:

Copyright 2010 the author

Additional Information:

Available for use in the Library and copying in accordance with the Copyright Act 1968, as amended. Thesis (PhD)--University of Tasmania, 2010. Includes bibliographical references. Ch. 1. General introduction -- Ch. 2. Literature review -- Ch. 3. General methodology -- Ch. 4. Evaluation of the Randox colorimetric serum copper and zinc assays against atomic absorption spectroscopy -- Ch. 5. Pilot study of trace element status in northern Tasmania -- Ch. 6. Population study of selenium, copper and zinc status -- General discussion and conclusions

Date Deposited: 25 Nov 2014 00:58
Last Modified: 11 Mar 2016 05:53
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