Supplement Scholar
Mineral

Selenomethionine

Buy on Amazon ↗

Affiliate link: we may earn a commission at no extra cost to you. Disclosures

Selenomethionine. Organic selenium form — preferred for thyroid (Hashimoto's) and antioxidant support.

How it works. Substitutes for methionine in proteins; releases Se for selenoprotein synthesis (GPx, deiodinases).

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

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

Side effects and interactions. 1 medication interaction listed. Serious: Selenosis at >400 mcg/d chronically.

Stacking. Pairs well with NAD+ precursor (NMN or NR), Omega-3.

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 Selenomethionine. Anecdotes are not medical advice.

Selenomethionine. Organic selenium form — preferred for thyroid (Hashimoto's) and antioxidant support.

Molecular structureC5H11NO2Se · 196.12 g/mol

What it is

Organic selenium form — preferred for thyroid (Hashimoto's) and antioxidant support.

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 OptimizationHealthy AgingFertility

How it works

Substitutes for methionine in proteins; releases Se for selenoprotein synthesis (GPx, deiodinases).

Pathways

  • Glutathione peroxidase
  • Type 1/2 deiodinase

Effects

  • ↓TPO antibody titers in Hashimoto's decreases

What the research supports

Reduces TPO antibody titers 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
100–200 mcg
TimingConsistent daily timing recommended; split larger doses if GI tolerance is a concern.
With foodOptional
Best formMost evidence is based on the chelated form (glycinate, bisglycinate, citrate, malate) form.
Upper limit400 mcg/d UL
Shop Selenomethionine on Amazon ↗

As an Amazon Associate I earn from qualifying purchases. Look for USP, NSF or Informed Sport seals before you buy.

Side effects & interactions

Serious

  • Selenosis at >400 mcg/d chronically

Medication interactions

Prescription medications (general)minor

Always disclose 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

  • NAD+ precursor (NMN or NR)Complementary mitochondrial and sirtuin support.
  • Omega-3Lowers inflammation and supports membrane integrity.

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.

Selenium supplementation and Hashimoto's thyroiditis ↗
Meta-analysis · Thyroid · 2010

Reduced TPO antibody titers and improved well-being.

PubMed: Selenomethionine — Reduces TPO antibody titers in Hashimoto's ↗
Systematic review · PubMed (NLM) · 2026

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

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

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

Discussion

Loading discussion…