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Mineral

Selenium (Selenomethionine)

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Selenium (Selenomethionine). Antioxidant trace element for thyroid.

How it works. Cofactor for glutathione peroxidase and deiodinases.

What the research supports. 1 graded claims. Strongest: Reduces thyroid antibodies (moderate).

How much to take. Typical dose: 100–200 mcg.

Side effects and interactions. 1 medication interaction listed. No serious side effects listed at normal doses.

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

Common forms. Available as Chelated form (glycinate, bisglycinate, citrate, malate), Inorganic salt (oxide, sulfate, chloride), Liquid ionic solution, Topical or transdermal preparation.

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

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

Selenium (Selenomethionine). Antioxidant trace element for thyroid.

Element Se · Z = 34Se · 78.97 g/mol

What it is

Antioxidant trace element for thyroid.

Food sources

Whole foods (leafy greens, legumes, nuts, seeds, seafood, animal proteins)Fortified foods such as cereals, breads, plant milks, and table saltMineral supplements as chelates, citrates, glycinates, or inorganic salts

Goals

Hormone BalanceImmune FunctionHealthy Aging

How it works

Cofactor for glutathione peroxidase and deiodinases.

Pathways

  • Cofactor for glutathione peroxidase
  • deiodinases

Effects

  • ↓thyroid antibodies decreases

What the research supports

Reduces thyroid antibodiesmoderate

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
100–200 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 chelated form (glycinate, bisglycinate, citrate, malate) form.
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Side effects & interactions

Common side effects

  • Selenosis at high doses

Medication interactions

Prescription medications (general)minor

Always disclose Selenium (Selenomethionine) 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.

Common forms

  • Chelated form (glycinate, bisglycinate, citrate, malate)
  • Inorganic salt (oxide, sulfate, chloride)
  • Liquid ionic solution
  • Topical or transdermal preparation

Key studies

8 studies cited in total.

PubMed: Selenium (Selenomethionine) — Reduces thyroid antibodies ↗
Systematic review · PubMed (NLM) · 2026

Opens current human and preclinical literature matching Selenium (Selenomethionine) and "Reduces thyroid antibodies". Filter by RCT, meta-analysis, or year on the results page.

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

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

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

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

Discussion

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