Randomized controlled trial of the effect of selenium supplementation on thyroid function in the elderly in the United Kingdom

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#aged #female #humans #hypothyroidism #male

Randomized controlled trial of the effect of selenium supplementation on thyroid function in the elderly in the United Kingdom

Rayman et al., 2008 | Am J Clin Nutr | Rct

Citation

Rayman Margaret P, Thompson Alexander J, ... Beckett Geoffrey J. Randomized controlled trial of the effect of selenium supplementation on thyroid function in the elderly in the United Kingdom. Am J Clin Nutr. 2008-Feb;87(2):370-8

Abstract

BACKGROUND: Thyroid function depends on the essential trace mineral selenium, which is at the active center of the iodothyronine deiodinase enzymes that catalyze the conversion of the prohormone thyroxine (T(4)) to the active form of thyroid hormone, triiodothyronine (T(3)). OBJECTIVE: Because selenium intake in the United Kingdom has fallen during the past 25 y, we wanted to determine whether current selenium status might be limiting conversion of T(4) to T(3) in the elderly, in whom marginal hypothyroidism is relatively common. DESIGN: We investigated the effect of selenium supplementation in a double-blind, placebo-controlled trial in 501 elderly UK volunteers. Similar numbers of men and women from each of 3 age groups, 60-64 y, 65-69 y, and 70-74 y, were randomly allocated to receive 100, 200, or 300 microg Se/d as high-selenium yeast or placebo yeast for 6 mo. As part of the study, plasma selenium, thyroid-stimulating hormone, and total and free T(3) and T(4) were measured. Data from 368 euthyroid volunteers who provided blood samples at baseline and 6 mo were analyzed. RESULTS: Although selenium status at baseline correlated weakly with free T(4) (r = -0.19, P < 0.001) and with the ratio of free T(3) to free T(4) (r = 0.12, P = 0.02), we found no evidence of any effect of selenium supplementation on thyroid function, despite significant increases in plasma selenium. However, baseline plasma selenium in our study (x: 91 microg/L) was somewhat higher than in previous supplementation studies in which apparently beneficial effects were seen. CONCLUSION: We found no indication for increasing selenium intake to benefit T(4) to T(3) conversion in the elderly UK population.

Key Findings

Although selenium status at baseline correlated weakly with free T(4) (r = -0.19, P < 0.001) and with the ratio of free T(3) to free T(4) (r = 0.12, P = 0.02), we found no evidence of any effect of selenium supplementation on thyroid function, despite significant increases in plasma selenium. However, baseline plasma selenium in our study (x: 91 microg/L) was somewhat higher than in previous supplementation studies in which apparently beneficial effects were seen.

Outcomes Measured

  • Requires manual extraction

Population

Field Value
Population See abstract
Sample Size See abstract
Age Range See abstract
Condition See abstract

MeSH Terms

  • Aged
  • Female
  • Humans
  • Hypothyroidism
  • Male
  • Middle Aged
  • Selenium
  • Selenium Compounds
  • Thyroid Function Tests
  • Thyrotropin
  • Thyroxine
  • Triiodothyronine
  • United Kingdom

Evidence Classification

  • Level: Rct
  • Publication Types: Journal Article, Randomized Controlled Trial, Research Support, Non-U.S. Gov't
  • Vertical: selenium-thyroid

Provenance

  • PMID: 18258627
  • DOI: (not available)
  • PMCID: Not in PMC
  • Verified: 2026-04-09 via PubMed E-utilities API

Source extracted via PubMed E-utilities API on 2026-04-09