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Selenium and iodine supplementation: effect on thyroid function of older New Zealanders
Christine D Thomson1, Jennifer M Campbell, Jody Miller
1Departments of Human Nutrition and Preventive and Social Medicine, University of Otago, Dunedin, New Zealand.
The American Journal of Clinical Nutrition
|August 21, 2009
Summary
Selenium supplementation improved glutathione peroxidase activity in older adults, while iodine intake corrected mild deficiency and reduced thyroglobulin levels. No combined benefits for thyroid function were observed.
Area of Science:
- Endocrinology
- Nutritional Science
- Gerontology
Background:
- New Zealand's population exhibits marginal selenium status and mild iodine deficiency.
- Optimal thyroid function necessitates adequate iodine and selenium intake.
Purpose of the Study:
- To assess if low selenium and iodine status negatively impacts thyroid function in elderly New Zealanders.
- Investigate the effects of selenium and iodine supplementation on thyroid health in older adults.
Main Methods:
- A double-blind, randomized, placebo-controlled trial involving 100 volunteers aged 60-80 years.
- Participants received selenium (l-selenomethionine), iodine, combined selenium and iodine, or placebo for 3 months.
- Measured thyroid-stimulating hormone, thyroid hormones, thyroglobulin, selenium, glutathione peroxidase activity, and urinary iodine concentration.
Main Results:
- Selenium supplementation increased plasma selenium and glutathione peroxidase activity.
- Iodine supplementation improved urinary iodine concentration and reduced thyroglobulin levels.
- No significant effects on thyroid-stimulating hormone or free thyroid hormones were observed; no synergistic effects of selenium and iodine were found.
Conclusions:
- Selenium supplementation enhances antioxidant status but does not improve thyroid hormone levels in older adults.
- Iodine supplementation effectively addresses iodine deficiency and reduces elevated thyroglobulin.
- Combined selenium and iodine supplementation did not show synergistic effects on thyroid function in this population.
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