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Effects of selenomethionine supplementation on selenium status and thyroid hormone concentrations in healthy adults
BACKGROUND: Selenium, a potential cancer prevention agent currently being tested against prostate cancer in the Selenium and Vitamin E Cancer Prevention Trial (SELECT), plays an integral role in thyroid metabolism. The effects of long-term selenium supplementation on thyroid hormone concentrations are unknown. OBJECTIVE: The objective was to investigate the effects of long-term selenium supplementation on thyroid hormone concentrations. DESIGN: Twenty-eight healthy adults took 200 μg selenomethionine/d for 28 mo. The thyroid hormones triiodothyronine (T₃), thyroxine (T₄), and thyrotropin (TSH) were measured in plasma for 4 mo before supplementation and quarterly during supplementation. The assay methods were changed midstudy; the results of the 2 methods were not comparable. Therefore, one analysis was conducted based on the results of the first method, and a second analysis was based on all of the data, adjusted for the change. Serial data collection permitted a test for trends rather than simply a difference between initial and final values. RESULTS: By 9 mo, mean (±SEM) plasma selenium concentrations had increased from 1.78 ± 0.07 μmol/L at baseline to 2.85 ± 0.11 μmol/L for men and from 1.64 ± 0.04 to 3.32 ± 0.1.2 μmol/L for women. T₃ concentrations in men increased 5% per year (P = 0.01). T₄ and TSH concentrations were unchanged. CONCLUSIONS: Selenium supplementation produced no clinically significant changes in thyroid hormone concentrations. A small but statistically significant increase in T₃ concentrations was noted in men, with no corresponding decreases in TSH. A subset of SELECT subjects might be monitored periodically for changes during long-term selenium supplementation.
Combs, Gerald F. Jr.
Midthune, Douglas N.
Patterson, Kristine Y.
Canfield, Wesley K.
Hill, A. David
Levander, Orville A.
Taylor, Philip R.
Moler, James E.
Patterson, Blossom H.
seleno amino acids
American journal of clinical nutrition AJN 2009 June, v. 89, no. 6
American Society for Clinical Nutrition
Journal Articles, USDA Authors, Peer-Reviewed
Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.
Agricultural Research Service
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