Supplement
Selenium
SaveSelenium is an essential trace mineral incorporated into selenoproteins that are critical for antioxidant defense, thyroid function, and immune regulation.
Quick verdict
Essential in deficiency states with clear thyroid and immune benefits. Supplementation in replete individuals may carry risks.
Evidence score
A rough internal score reflecting quantity, quality, and consistency of human evidence. Not a clinical recommendation.
What the research shows
Strong evidence for thyroid autoimmunity (Hashimoto's). SELECT trial showed no cancer prevention benefit and potential diabetes risk at 200 mcg. Benefits are most clear in selenium-deficient populations.
Benefits
- Essential for thyroid hormone metabolism
- Supports glutathione peroxidase function
- May reduce thyroid antibodies in Hashimoto's
- Supports immune function in deficiency
Dosage notes
55–200 mcg daily. RDA is 55 mcg. Do not exceed 400 mcg/day. Selenomethionine is the best-absorbed form.
Side effects
- Garlic breath and metallic taste at high doses
- Hair and nail brittleness
- GI disturbance
- Selenosis at chronic high intake
Who should be cautious
Narrow therapeutic window. Chronic intake above 400 mcg/day risks selenosis. SELECT trial raised concerns about prostate cancer and diabetes risk.
What this page cannot tell you
Benefits depend on baseline selenium status. Those already replete (>120 mcg/L plasma) are unlikely to benefit and may be harmed.
Leaderboard scores
- Immunity60
- Longevity50
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