Does selenium supplementation affect thyroid function? Results from a randomized, controlled, double-blinded trial in a Danish population

Kristian Hillert Winther, Steen Joop Bonnema, Frederik Cold, Birgit Debrabant, Mads Nybo, Søren Cold, Laszlo Hegedüs

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

OBJECTIVE: Selenium is present in the active site of proteins important for thyroid hormone synthesis and metabolism. The objective of this study is to investigate the effect of selenium supplementation in different doses on thyroid function, under conditions of suboptimal dietary selenium intake.

DESIGN: The Danish PREvention of Cancer by Intervention with SElenium pilot study (DK-PRECISE) is a randomized, double-blinded, placebo-controlled trial. A total of 491 males and females aged 60-74 years were randomized to 100 μg (n=124), 200 μg (n=122), or 300 μg (n=119) selenium-enriched yeast or matching yeast-based placebo tablets (n=126). A total of 361 participants, equally distributed across treatment groups, completed the 5-year intervention period.

METHODS: Plasma samples were analyzed for selenium and serum samples for TSH, free triiodothyronine (FT3), and free thyroxine (FT4) at baseline, and after 6 months, and 5 years of supplementation.

RESULTS: Plasma selenium concentrations increased significantly and dose-dependently in treatment groups receiving selenium (P<0.001). Serum TSH and FT4 concentrations decreased significantly and dose-dependently by 0.066 mIU/l (P=0.010) and 0.11 pmol/l (P=0.015), respectively, per 100 μg/day increase, with insignificant differences between 6 months and 5 years. No significant effects were found for FT3 and FT3:FT4 ratio.

CONCLUSIONS: In euthyroid subjects, selenium supplementation minutely and dose-dependently affects thyroid function, when compared with placebo, by decreasing serum TSH and FT4 concentrations. Based on these findings, selenium supplementation is not warranted under conditions of marginal selenium deficiency. However, a role for selenium supplementation in the treatment of autoimmune thyroid diseases is still unresolved.

Original languageEnglish
JournalEuropean Journal of Endocrinology
Volume172
Issue number6
Pages (from-to)657-667
ISSN0804-4643
DOIs
Publication statusPublished - Jun 2015

Fingerprint Dive into the research topics of 'Does selenium supplementation affect thyroid function? Results from a randomized, controlled, double-blinded trial in a Danish population'. Together they form a unique fingerprint.

Cite this