BioStacks

Best Selenium for Immune

Top 10 products ranked

Last reviewed May 2026

Clinical dose: 100–200 mcg

Why Selenium for Immune

Selenium plays a supporting role in immune. Essential component of selenoproteins including glutathione peroxidase (antioxidant defense) and deiodinases (thyroid hormone activation). Selenomethionine is the most bioavailable supplemental form, while sodium selenite is inorganic and less efficiently absorbed.

What dose to look for

Clinical studies typically use 100–200 mcg of selenium. Common supplement dose; UL is 400 mcg/day. Products below this range may not deliver meaningful results.

What form to look for

Avoid sodium selenite — inorganic, lower retention. Look for selenomethionine for better absorption.

What the research says

Selenium has strong clinical evidence for immune benefits. SELECT trial (35,000+ men) found no cancer prevention benefit; essential for thyroid via selenoproteins Learn more

Clinical research on Selenium

MODERATE — Essential for immune function; deficiency impairs viral defense · 55–200 mcg/day (as selenomethionine or selenium yeast)

•2019 systematic review found selenium supplementation enhanced immune cell function (NK cell activity, T-cell proliferation) and improved response to vaccination, primarily in selenium-deficient populations. PubMed
•Selenium deficiency is associated with increased virulence of certain viruses — Keshan disease (coxsackievirus B3 cardiomyopathy) is a direct result of selenium deficiency in endemic areas of China.
•Selenoproteins (glutathione peroxidases, thioredoxin reductases) are critical for antioxidant defense in immune cells. Low selenium status is associated with poorer outcomes in viral infections including HIV.
•Caution: narrow therapeutic window. Toxicity (selenosis) can occur at >400 mcg/day. Brazil nuts contain highly variable selenium — 1 nut can provide 10–90 mcg.

See full Immune research →