Supplement Scholar
Mineral

Selenium

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Selenium. Trace mineral essential for glutathione peroxidase and thyroid hormone activation.

How it works. Incorporated into selenoproteins including glutathione peroxidase and deiodinases (T4→T3).

What the research supports. 1 graded claims. Strongest: Reduces TPO antibodies in Hashimoto's (moderate).

How much to take. Typical dose: 55–200 mcg.

Side effects and interactions. 1 medication interaction listed. Serious: Selenosis (hair loss, nail brittleness) >400 mcg/d.

Stacking. Pairs well with Vitamin D3 + K2, Zinc, NAD+ precursor (NMN or NR).

Forms. 2 forms. Pick one to open its profile.

Key studies. 8 studies cited. The strongest are listed with links to PubMed.

Community. Experiences from people who have tried Selenium. Anecdotes are not medical advice.

Selenium. Trace mineral essential for glutathione peroxidase and thyroid hormone activation.

Element Se · Z = 34Se · 78.97 g/mol

What it is

Trace mineral essential for glutathione peroxidase and thyroid hormone activation.

Also called

Selenomethionine

Food sources

Brazil nutsSeafoodOrgan meats

Goals

Immune FunctionHormone OptimizationHealthy Aging

How it works

Incorporated into selenoproteins including glutathione peroxidase and deiodinases (T4→T3).

Pathways

  • Antioxidant defense
  • Thyroid hormone activation

Effects

  • +Thyroid hormone conversion supports
  • +Antioxidant defense supports

What the research supports

Reduces TPO antibodies in Hashimoto'smoderate

Strong: consistent results across large trials or meta-analyses. Moderate: several trials, mostly positive. Limited: small or mixed studies. Preclinical: animal or cell research only.

Typical dose
55–200 mcg
TimingConsistent daily timing recommended; split larger doses if GI tolerance is a concern.
With foodEither with or without food.
Best formMost evidence is based on the selenomethionine form.
Upper limit400 mcg
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Side effects & interactions

Serious

  • Selenosis (hair loss, nail brittleness) >400 mcg/d

Medication interactions

Prescription medications (general)minor

Always disclose Selenium use to your prescriber — additive, antagonistic, or pharmacokinetic interactions are possible.

Check any supplement–medication combination with your pharmacist before starting.

Combines with

Pairs well

  • Vitamin D3 + K2Foundational immune modulation.
  • ZincRequired cofactor for innate and adaptive immune function.
  • NAD+ precursor (NMN or NR)Complementary mitochondrial and sirtuin support.

Key studies

8 studies cited in total.

PubMed: Selenium — Reduces TPO antibodies in Hashimoto's ↗
Systematic review · PubMed (NLM) · 2026

Opens current human and preclinical literature matching Selenium and "Reduces TPO antibodies in Hashimoto's". Filter by RCT, meta-analysis, or year on the results page.

PubMed: Selenium — randomized controlled trial ↗
Systematic review · PubMed (NLM) · 2026

Opens current human and preclinical literature matching Selenium and "randomized controlled trial". Filter by RCT, meta-analysis, or year on the results page.

PubMed: Selenium — meta-analysis ↗
Systematic review · PubMed (NLM) · 2026

Opens current human and preclinical literature matching Selenium and "meta-analysis". Filter by RCT, meta-analysis, or year on the results page.

Discussion

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