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Selenium

Mineral4 forms compared ↓

Also known as: Selenium glycinate

A
Grade A
💊 100-200mcg daily🎯 10 primary uses🔗 3 synergies⚠️ Review warnings

Overview

Essential trace mineral for glutathione peroxidase activity, thyroid function, and optimal immune response to viral infections.

Primary Uses
Antioxidant enzyme supportThyroid functionViral immunitySelenoprotein productionT4 to T3 conversionThyroid protectionAutoimmune thyroid (Hashimoto's)Prostate healthAntioxidantProstate cancer (controversial)

Compare Forms

4 forms

Different chemical forms vary in absorption, side effects, and best use cases. Higher bioavailability scores indicate better absorption.

Selenomethionine

HIGH 100

Selenium bound to methionine amino acid

Best for:General supplementationBuilding selenium stores

💡 Excellent. Well-absorbed and stored in body proteins.

✅ Pros
  • • Best absorbed
  • • Builds stores
  • • Natural form
⚠️ Cons
  • • Can accumulate - don't exceed RDA long-term

📝 Best for maintaining selenium status

Methylselenocysteine

HIGH 95

Methylated selenium compound

Best for:Cancer prevention researchDetoxification

💡 Excellent. Unique metabolism pathway.

✅ Pros
  • • Unique benefits
  • • Cancer research
  • • Well-tolerated
⚠️ Cons
  • • More expensive
  • • Less common

📝 Research-backed for specific applications

Selenium Yeast

HIGH 85

Selenium-enriched yeast

Best for:Food-based supplementation

💡 Good. Multiple selenium forms.

✅ Pros
  • • Food-based
  • • Multiple forms
  • • Well-absorbed
⚠️ Cons
  • • Yeast sensitivity
  • • Variable content

📝 Good option for food-form preference

Sodium Selenite

GOOD 70

Inorganic selenium form

Best for:Budget optionShort-term use

💡 Moderate. Pro-oxidant at high doses.

✅ Pros
  • • Inexpensive
⚠️ Cons
  • • Pro-oxidant potential
  • • Lower retention
  • • Less natural

📝 Organic forms (selenomethionine) preferred

Dosage

Typical range
100-200mcg daily
Timing
With meals
With food
Yes
Dose Tiers
RDA / DV
55 mcg
Moderate
100-200 mcg
Optimal
100-200 mcg selenomethionine
Upper Limit
400 mcg
Duration

Ongoing for thyroid support

Special Populations

Hashimoto's, hypothyroid, those on iodine

Mechanism of Action

  • • Required for deiodinase enzymes
  • • Converts T4 to active T3
  • • Protects thyroid from oxidative damage
  • • May reduce thyroid antibodies

Evidence Quality

Evidence Grade A

Well-established for thyroid function and protection

Safety & Contraindications

Serious Warnings
  • • Toxicity above 400mcg chronically
  • • Narrow therapeutic window
Contraindications
  • • Excessive supplementation
Common Side Effects
  • • Garlic breath (high dose)
  • • GI upset
Pregnancy & Breastfeeding

Consult healthcare provider

Liver & Kidney Notes

Safe at normal doses

Interactions

💊 Medications
  • • May affect thyroid medication needs
🧪 Supplements
  • • Essential partner to iodine
  • • Works with zinc
🍽️ Food & Alcohol
  • • With food

Stacking & Synergies

Pairs Well With
IodineZincVitamin E
Avoid Combining With
Excessive doses
Best Goal Synergies
T4 to T3 conversionThyroid protection

Buying Guide

What to Look For
  • • Selenomethionine form
  • • 200mcg or less daily
Standardization Markers
Mcg seleniumForm (selenomethionine best)
Adulteration risk
Low
Practical Notes
  • • Don't exceed 400mcg daily
  • • Brazil nuts are rich source
  • • Important for thyroid
  • • Critical for T4→T3 conversion
  • • Protects thyroid when using iodine
  • • Don't exceed 200mcg daily
  • • SELECT trial caution - don't exceed 200mcg
  • • 1-2 Brazil nuts provides selenium
  • • Moderate doses only
Tags
immunemineralthyroidantioxidanthashimoto'sprostatecontroversial

Frequently Asked About Selenium

How much Selenium should I take?
The typical effective range is 100-200 mcg selenomethionine. Individual needs vary based on age, body weight, diet, and goals — start at the lower end and adjust based on response. Always consult a healthcare provider before starting a new supplement.
When is the best time to take Selenium?
With meals. Consistency matters more than perfect timing — pick a daily anchor (e.g. with breakfast or before bed) and stick with it.
Should I take Selenium with food?
Yes.
What is the best form of Selenium?
Selenomethionine is generally the best-absorbed form (Selenium bound to methionine amino acid). Cheaper forms exist but often deliver less usable Selenium per dose.
Does Selenium interact with medications?
Yes — known interactions include May affect thyroid medication needs. If you take any prescription medication, talk to your doctor or pharmacist before starting Selenium.
What does Selenium pair well with?
Selenium stacks well with Iodine, Zinc, and Vitamin E — these combinations either improve absorption or work synergistically toward common goals.
Who should not take Selenium?
Selenium should be avoided or used with caution by people with Excessive supplementation. Pregnant or breastfeeding women should consult a healthcare provider before use.

Top Products with Selenium

Highest-scored catalog products containing Selenium, ranked by our scoring engine.

Browse all Selenium products →

Related Guides

In-depth guides covering Selenium — protocols, comparisons, and use cases.

Educational content based on published research and our scoring methodology. Not medical advice — consult a qualified healthcare provider before starting, stopping, or changing supplements, especially if you take medications, are pregnant, or have a medical condition.