Selenium and zinc in hair and toenails in relation to the physical and mental health status of older adults: The Freemasons Health study in New Zealand

Authors

  • Shaheenul Islam,

    1. Neurology and Mental Health Division, The George Institute for International Health, Royal Prince Alfred Hospital and The University of Sydney, Sydney, New South Wales, Australia
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  • Kristie Carter,

    1. Neurology and Mental Health Division, The George Institute for International Health, Royal Prince Alfred Hospital and The University of Sydney, Sydney, New South Wales, Australia
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  • Cliona Ni Mhurchu,

    1. Clinical Trials Research Unit, University of Auckland, Auckland, New Zealand
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  • Craig S Anderson

    1. Neurology and Mental Health Division, The George Institute for International Health, Royal Prince Alfred Hospital, The University of Sydney, Sydney, New South Wales, Australia, and Clinical Trials Research Unit, University of Auckland, Auckland, New Zealand
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Correspondence to: Professor Craig Anderson, Director, Neurology and Mental Health Division, The George Institute for International Health. Email: canderson@george.org.au

Abstract

Objectives: To determine the associations of selenium and zinc on health.

Methods: A cross-sectional study; adults (mean age 65 years), Freemasons or spouses resident of the North Island of New Zealand; measures of cognition, the Timed Up and Go (TUG) test, and hair and toenail zinc and selenium levels. Multivariable logistic regression was used to determine significant associations.

Results: Univariate analyses showed a significant association of decreased likelihood of impaired performance (> 9.5 seconds) on the TUG test with increasing quartiles of nail selenium (odds ratio 0.73; 95% confidence interval 0.61–0.87). The association persisted in a multivariate model. No associations were seen for any of the other measures.

Conclusion: Low nail selenium levels were associated with impaired physical function, as a result of chance from multiplicity problems, bias or a true adverse effect of selenium deficiency. Prospective studies are necessary to more reliably discern temporal associations of micronutrients on health.

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