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Types of Selenium (Thyroid): Forms & Bioavailability

Evidence:Strong
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This content is for informational purposes only and does not constitute medical advice. Statements about dietary supplements have not been evaluated by the FDA and are not intended to diagnose, treat, cure, or prevent any disease. Individual results may vary — consult your healthcare provider before starting any supplement. Full disclaimer

Forms Comparison

FormBioavailabilityBest For
SelenomethionineHigh (>90% absorbed)General thyroid support — most studied form, incorporated into body proteins
Selenium YeastHighWhole-food form — contains multiple selenium species including selenomethionine
Sodium SeleniteModerate (50-60%)Budget option — inorganic form, less well-retained in tissue

Selenomethionine

Bioavailability: High (>90% absorbed). Best for: General thyroid support — most studied form, incorporated into body proteins.

Selenium Yeast

Bioavailability: High. Best for: Whole-food form — contains multiple selenium species including selenomethionine.

Sodium Selenite

Bioavailability: Moderate (50-60%). Best for: Budget option — inorganic form, less well-retained in tissue.

Full Selenium (Thyroid) Guide

References

  1. RCTGärtner R, Gasnier BC, Dietrich JW, Krebs B, Angstwurm MW (2002). Selenium supplementation in patients with autoimmune thyroiditis decreases thyroid peroxidase antibodies concentrations. Journal of Clinical Endocrinology & Metabolism. DOI PubMed
  2. RCTMarcocci C, Kahaly GJ, Krassas GE, Bartalena L, Prummel M, Stahl M, Altea MA, Nardi M, Pitz S, Boboridis K, Sivelli P, von Arx G, Mourits MP, Baldeschi L, Bencivelli W, Wiersinga W (2011). Selenium and the course of mild Graves' orbitopathy. New England Journal of Medicine. DOI PubMed
  3. RCTNegro R, Greco G, Mangieri T, Pezzarossa A, Dazzi D, Hassan H (2007). The influence of selenium supplementation on postpartum thyroid status in pregnant women with thyroid peroxidase autoantibodies. Journal of Clinical Endocrinology & Metabolism. DOI PubMed