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ING-097Ingredient Research Profile

Minerals

Selenium (Selenomethionine)

Also known as: Selenomethionine · Sodium selenite · Selenium yeast

●●●Strong Evidence

Trace mineral essential for glutathione peroxidase (antioxidant defence), thyroid hormone conversion, and sperm motility. Selenomethionine is the superior bioavailable form.

Effective Dose

55–200mcg / day

per clinical evidence

Evidence Level

Strong

Minerals

Mechanism

Selenoprotein co-factor — glutathione peroxidase, thyroid deiodinase, thioredoxin reductase

primary action

Best For

Thyroid health

Antioxidant defence, Immune function, Male fertility

This profile is for informational purposes only and does not constitute medical advice. Consult a qualified healthcare professional before starting any supplementation, especially if you have pre-existing conditions or take medications.

What Is Selenium (Selenomethionine)?

Selenium is incorporated into selenoproteins via selenocysteine — the 21st amino acid. The 25 known human selenoproteins perform critical functions in antioxidant defence (glutathione peroxidases), thyroid metabolism (iodothyronine deiodinases that convert T4 to active T3), and cellular redox signalling (thioredoxin reductases).

How It Works: The Science

Glutathione peroxidase (GPx1–4) uses selenocysteine to reduce hydrogen peroxide and lipid hydroperoxides to water and alcohols — the primary enzymatic defence against oxidative damage. Deiodinase I and II convert thyroxine (T4) to active triiodothyronine (T3) in thyroid and peripheral tissues. Selenoprotein P transports selenium in plasma.

Primary Mechanism

Selenoprotein co-factor — glutathione peroxidase, thyroid deiodinase, thioredoxin reductase

Evidence-Based Benefits

Supports thyroid hormone activation (T4 → T3)

strong

Biochemical consensus — selenium deficiency directly impairs T3 production

Reduces thyroid antibodies in Hashimoto's thyroiditis

moderate

Toulis et al. (2010) meta-analysis — 200mcg/day reduced TPO and Tg antibodies

Improves sperm motility and reduces male infertility

moderate

Scott et al. (1998) — 100mcg/day improved sperm motility in selenium-deficient men

Dosage Guide

Effective Dose

55–200mcg / day

55mcg/day RDA; 100–200mcg for therapeutic use. Selenomethionine has 90% bioavailability vs ~50% for inorganic selenite. Upper tolerable limit: 400mcg/day. Selenium content in food varies dramatically by soil selenium levels.

Safety Profile & Side Effects

Narrow therapeutic window. Toxicity (selenosis) occurs above 400mcg/day chronically — brittle hair/nails, garlic breath, neurological symptoms. Stay under 400mcg/day total (diet + supplement).

Who Should (and Shouldn't) Take It

Best for

Thyroid healthAntioxidant defenceImmune functionMale fertility

Who it's for

Those living in low-selenium soil regions (UK, parts of Europe, China, New Zealand), Hashimoto's patients, those with thyroid concerns, and men with fertility issues.

Frequently Asked Questions

What is the recommended dose of Selenium (Selenomethionine)?

Is Selenium (Selenomethionine) safe?

Narrow therapeutic window. Toxicity (selenosis) occurs above 400mcg/day chronically — brittle hair/nails, garlic breath, neurological symptoms. Stay under 400mcg/day total (diet + supplement).

How does Selenium (Selenomethionine) work?

Who should take Selenium (Selenomethionine)?

Those living in low-selenium soil regions (UK, parts of Europe, China, New Zealand), Hashimoto's patients, those with thyroid concerns, and men with fertility issues.

Related Ingredients

Iodine (Potassium Iodide)Zinc (Bisglycinate / Picolinate)Vitamin E (Mixed Tocopherols)N-Acetyl Cysteine (NAC)

Medical Disclaimer

Ingredient profiles are for informational purposes only and do not constitute medical advice. Consult a qualified healthcare professional before starting any supplementation, especially if you have pre-existing conditions or take medications. Full disclaimer →