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Selenium and iodine supplementation: effect on thyroid function of older New Zealanders.
Am J Clin Nutr. 2009 Oct; 90(4):1038-46.AJ

Abstract

BACKGROUND

The New Zealand population has both marginal selenium status and mild iodine deficiency. Adequate intakes of iodine and selenium are required for optimal thyroid function.

OBJECTIVE

The aim of the study was to determine whether low selenium and iodine status compromises thyroid function in an older New Zealand population.

DESIGN

We investigated the effects of selenium and iodine supplementation in a double-blind, randomized, placebo-controlled trial in 100 Dunedin volunteers aged 60-80 y. Participants received 100 microg Se/d as l-selenomethionine, 80 microg I, 100 microg Se + 80 microg I, or placebo for 3 mo. Thyroid-stimulating hormone (TSH), free triiodothyronine (T(3)), free thyroxine (T(4)), thyroglobulin, plasma selenium, whole-blood glutathione peroxidase (GPx) activity, and urinary iodine concentrations (UICs) were measured.

RESULTS

Plasma selenium (P < 0.0001) and whole-blood GPx activity (P<0.0001) increased from baseline to week 12 in the selenium and selenium plus iodine groups in comparison with the placebo group. Median UIC at baseline was 48 microg/L (interquartile range: 31-79 microg/L), which is indicative of moderate iodine deficiency. UIC increased in the iodine and selenium plus iodine groups and was significant only for the iodine group (P = 0.0014). Thyroglobulin concentration decreased by 24% and 13% of baseline in the iodine and selenium plus iodine groups in comparison with the placebo group (P = 0.009 and P = 0.108, respectively). No significant treatment effects were found for TSH, free T(3), free T(4), or ratio of T(3) to T(4).

CONCLUSIONS

Additional selenium improved GPx activity but not the thyroid hormone status of older New Zealanders. Iodine supplementation alleviated the moderate iodine deficiency and reduced elevated thyroglobulin concentrations. No synergistic action of selenium and iodine was observed. The trial was registered at www.anzctr.org.au/registry/ as ACTRN012605000368639.

Authors+Show Affiliations

Departments of Human Nutrition and Preventive and Social Medicine, University of Otago, Dunedin, New Zealand.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Randomized Controlled Trial
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

19692495

Citation

Thomson, Christine D., et al. "Selenium and Iodine Supplementation: Effect On Thyroid Function of Older New Zealanders." The American Journal of Clinical Nutrition, vol. 90, no. 4, 2009, pp. 1038-46.
Thomson CD, Campbell JM, Miller J, et al. Selenium and iodine supplementation: effect on thyroid function of older New Zealanders. Am J Clin Nutr. 2009;90(4):1038-46.
Thomson, C. D., Campbell, J. M., Miller, J., Skeaff, S. A., & Livingstone, V. (2009). Selenium and iodine supplementation: effect on thyroid function of older New Zealanders. The American Journal of Clinical Nutrition, 90(4), 1038-46. https://doi.org/10.3945/ajcn.2009.28190
Thomson CD, et al. Selenium and Iodine Supplementation: Effect On Thyroid Function of Older New Zealanders. Am J Clin Nutr. 2009;90(4):1038-46. PubMed PMID: 19692495.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Selenium and iodine supplementation: effect on thyroid function of older New Zealanders. AU - Thomson,Christine D, AU - Campbell,Jennifer M, AU - Miller,Jody, AU - Skeaff,Sheila A, AU - Livingstone,Vicki, Y1 - 2009/08/19/ PY - 2009/8/21/entrez PY - 2009/8/21/pubmed PY - 2009/10/10/medline SP - 1038 EP - 46 JF - The American journal of clinical nutrition JO - Am. J. Clin. Nutr. VL - 90 IS - 4 N2 - BACKGROUND: The New Zealand population has both marginal selenium status and mild iodine deficiency. Adequate intakes of iodine and selenium are required for optimal thyroid function. OBJECTIVE: The aim of the study was to determine whether low selenium and iodine status compromises thyroid function in an older New Zealand population. DESIGN: We investigated the effects of selenium and iodine supplementation in a double-blind, randomized, placebo-controlled trial in 100 Dunedin volunteers aged 60-80 y. Participants received 100 microg Se/d as l-selenomethionine, 80 microg I, 100 microg Se + 80 microg I, or placebo for 3 mo. Thyroid-stimulating hormone (TSH), free triiodothyronine (T(3)), free thyroxine (T(4)), thyroglobulin, plasma selenium, whole-blood glutathione peroxidase (GPx) activity, and urinary iodine concentrations (UICs) were measured. RESULTS: Plasma selenium (P < 0.0001) and whole-blood GPx activity (P<0.0001) increased from baseline to week 12 in the selenium and selenium plus iodine groups in comparison with the placebo group. Median UIC at baseline was 48 microg/L (interquartile range: 31-79 microg/L), which is indicative of moderate iodine deficiency. UIC increased in the iodine and selenium plus iodine groups and was significant only for the iodine group (P = 0.0014). Thyroglobulin concentration decreased by 24% and 13% of baseline in the iodine and selenium plus iodine groups in comparison with the placebo group (P = 0.009 and P = 0.108, respectively). No significant treatment effects were found for TSH, free T(3), free T(4), or ratio of T(3) to T(4). CONCLUSIONS: Additional selenium improved GPx activity but not the thyroid hormone status of older New Zealanders. Iodine supplementation alleviated the moderate iodine deficiency and reduced elevated thyroglobulin concentrations. No synergistic action of selenium and iodine was observed. The trial was registered at www.anzctr.org.au/registry/ as ACTRN012605000368639. SN - 1938-3207 UR - https://www.unboundmedicine.com/medline/citation/19692495/Selenium_and_iodine_supplementation:_effect_on_thyroid_function_of_older_New_Zealanders_ L2 - https://academic.oup.com/ajcn/article-lookup/doi/10.3945/ajcn.2009.28190 DB - PRIME DP - Unbound Medicine ER -