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Deficiency/Hormonal

Selenium

Essential trace mineral that corrects low selenium status and may support thyroid health in adults with low intake.

Selenium
58
score
B
evidence
Caution
risk

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Use with caution

This supplement may interact with medications, medical conditions or sensitive populations. Review safety before use.

Quick Take

Worth considering if your intake is low or thyroid antibodies are a concern — otherwise avoid piling on extra selenium.

Selenium is an essential trace mineral found in Brazil nuts, seafood, meat, eggs, and grains grown in selenium-rich soil. It is built into selenoproteins that help control antioxidant defense and activate thyroid hormones. Best-supported uses are correcting low selenium status, modestly lowering thyroid autoantibodies in some people, and possibly improving immune and fertility markers when intake is low. People with low dietary intake or confirmed low blood selenium benefit most.

Potential benefits

01
Corrects selenium deficiency
02
May lower TPO antibodies
03
May improve sperm motility
04
May improve viral clearance
05
May improve thyroid wellbeing
06
May reduce hair/nail changes

Protocol

Amount
100-200 mcg
Frequency
Once daily
When
With food is fine; consistency and total daily intake matter more than exact timing.

Onset Time

2-8 weeks for blood levels; 3-6 months for thyroid or fertility outcomes

Who Should Consider

Adults with very low seafood, egg, or meat intake
Vegans in low-selenium soil regions
People with confirmed low serum or plasma selenium
Adults with thyroid antibodies discussing options
Men with poor semen motility and low intake

Food Sources

  • Brazil nuts (~50-90 mcg per nut; highly variable)
  • Tuna (~90 mcg per 85 g)
  • Sardines (~45 mcg per 85 g)
  • 2 eggs (~25-30 mcg total)
  • Turkey (~30 mcg per 85 g)
  • Cottage cheese (~20 mcg per cup)

How It Works

Selenium is incorporated into selenoproteins such as glutathione peroxidases and deiodinases. These enzymes help neutralize peroxides and convert thyroid hormone T4 into active T3, so low intake can impair antioxidant defense, thyroid regulation, and some immune responses.

Updated 5/19/2026

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