Selenium
minerals
Selenium is an essential trace mineral that functions as a cofactor for selenoproteins, including glutathione peroxidase, which protects cells from oxidative damage. It plays crucial roles in thyroid hormone metabolism, immune function, and reproductive health. Most people obtain adequate selenium through diet, particularly from Brazil nuts, fish, and eggs.
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Benefits
Dosage
Typical Dose
55–200 mcg daily
Upper Limit
400 mcg daily (UL for adults)
Timing
With meals to enhance absorption; consistent daily timing
Forms & Bioavailability
Selenomethionine
Highest bioavailability; incorporated into proteins; preferred supplemental form
Sodium selenite
Moderate bioavailability; inorganic form; less efficiently retained
Selenocysteine
High bioavailability; naturally occurring form in foods
Side Effects
Interactions
Research Summary
Selenium is well-established as essential for human health, with robust evidence supporting its role in antioxidant defence and thyroid function. Research shows mixed results for cancer prevention and cardiovascular outcomes; whilst some studies suggest protective effects, large trials have not consistently demonstrated clinically significant benefits beyond correcting deficiency. Most evidence supports maintaining adequate intake through diet rather than high-dose supplementation for healthy individuals.
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The Bottom Line on Selenium
Selenium is well-researched with strong evidence supporting its primary benefits.It is most commonly used for antioxidant protection through selenoprotein synthesis and thyroid hormone metabolism and immune function. As with any supplement, individual results vary. Start with the lower end of the dosage range and assess for 4-8 weeks before adjusting.
About Our Research
This profile is compiled from peer-reviewed research published on PubMed, the NIH Office of Dietary Supplements, and established nutritional science databases. Dosages reflect clinically-studied amounts from human trials where available. We update profiles as new research emerges. This is not medical advice — consult a healthcare professional before supplementing.
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