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evidence · mechanism · dose
Supplements/Mineral

Selenomethionine

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

Hormone OptimizationHealthy AgingFertility

Overview

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

Natural sources
    Common forms

      Forms & variants of Selenium

      Different chemical forms of Selenium behave differently. Browse each form's mechanism, bioavailability, and best-use context.

      Parent
      Selenium

      Trace mineral essential for glutathione peroxidase and thyroid hormone activation.

      Selenium yeast
      Selenium-Enriched Yeast

      Yeast-bound selenomethionine — form used in major chemoprevention trials.

      Mechanism of action

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

      Pathways
      • · Glutathione peroxidase
      • · Type 1/2 deiodinase

      Effects on the body

      Organ system effects

      Evidence-based benefits

      Reduces TPO antibody titers in Hashimoto's

      Moderate evidence

      Potential side effects

      Common
        Rare
        • · Garlic breath at high dose
        Serious
        • · Selenosis at >400 mcg/d chronically

        Drug interactions

        No notable interactions reported.

        Supplement interactions

        Pairs well with

        None listed.

        Avoid combining with

        No specific avoidances listed.

        Dosing & bioavailability

        Typical dose
        100–200 mcg
        Upper safe limit
        400 mcg/d UL
        With food?
        Optional

        Where to buy

        Affiliate-style search links to reputable retailers. We don't endorse specific brands — verify third-party testing (USP, NSF, Informed Sport) before purchase.

        Mineral
        Selenomethio…
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        iHerb
        Global delivery · curated brands
        Mineral
        Selenomethio…
        Thorne
        Practitioner-grade · NSF tested

        Scientific evidence (8)

        Meta-analysisThyroid · 2010

        Selenium supplementation and Hashimoto's thyroiditis

        Toulis KA, et al.

        Meta-analysis of selenium in Hashimoto's.

        Key findings

        Reduced TPO antibody titers and improved well-being.

        Open study
        Systematic reviewPubMed (NLM) · 1970

        PubMed: Selenomethionine — Reduces TPO antibody titers in Hashimoto's

        Live PubMed search

        Live results for "Selenomethionine Reduces TPO antibody titers in Hashimoto's" across the PubMed/MEDLINE peer-reviewed index.

        Key findings

        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.

        Open study
        Systematic reviewPubMed (NLM) · 1970

        PubMed: Selenomethionine — randomized controlled trial

        Live PubMed search

        Live results for "Selenomethionine randomized controlled trial" across the PubMed/MEDLINE peer-reviewed index.

        Key findings

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

        Open study
        Systematic reviewPubMed (NLM) · 1970

        PubMed: Selenomethionine — meta-analysis

        Live PubMed search

        Live results for "Selenomethionine meta-analysis" across the PubMed/MEDLINE peer-reviewed index.

        Key findings

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

        Open study
        Systematic reviewPubMed (NLM) · 1970

        PubMed: Selenomethionine — pharmacokinetics

        Live PubMed search

        Live results for "Selenomethionine pharmacokinetics" across the PubMed/MEDLINE peer-reviewed index.

        Key findings

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

        Open study
        Systematic reviewPubMed (NLM) · 1970

        PubMed: Selenomethionine — safety adverse events

        Live PubMed search

        Live results for "Selenomethionine safety adverse events" across the PubMed/MEDLINE peer-reviewed index.

        Key findings

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

        Open study
        Systematic reviewPubMed (NLM) · 1970

        PubMed: Selenomethionine — dose response

        Live PubMed search

        Live results for "Selenomethionine dose response" across the PubMed/MEDLINE peer-reviewed index.

        Key findings

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

        Open study
        Systematic reviewGoogle Scholar · 1970

        Google Scholar: Selenomethionine — clinical evidence

        Live Scholar search

        Cross-database citation index for Selenomethionine as it relates to "clinical evidence".

        Key findings

        Includes preprints, theses, and journal articles. Useful for tracking citation counts and follow-on work.

        Open study
        Educational use only. This profile is not medical advice. Consult a qualified healthcare professional before starting any supplement, especially if you take prescription medication or have a chronic condition.