Selenium: what it means.
Written to our editorial standards · reviewed against published research· Updated 27 Jun 2026
Typical reference bands (µg/dL)
Lowunder 70 µg/dL
Optimal90-150 µg/dL
Ranges vary by laboratory, age, and sex, your lab's own reference range always takes precedence.
Common causes
- Low-selenium soils and diet
- Malabsorption
- A diet lacking Brazil nuts, seafood, or organ meats
What it can feel like
- Often silent; a marked shortfall can affect thyroid and immune function
Who should test
Relevant with thyroid concerns or a restricted diet. Selenium has a fairly narrow safe range, so avoid stacking several high-dose sources.
Supplements that help raise Selenium
Evidence-led, and only a piece of the picture, diet, lifestyle, and your clinician matter most.
Selenium is a cofactor for the enzymes that convert thyroid T4 into active T3 and that recycle antioxidants; a modest dose restores this without tipping into excess.
Shop the top pick for selenium
Recommended
NOW Foods, Selenium 200mcg Yeast Free
180 veg capsules · ~$12 · ★ 4.8
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Common questions
What does a low Selenium mean?
Common drivers include low-selenium soils and diet; malabsorption; a diet lacking Brazil nuts, seafood, or organ meats. A result outside the optimal range is best read in context: discuss it with your clinician, who can weigh the full picture and your lab's own reference range.
What supplements help raise Selenium?
Evidence-led options include Selenium. They support, but don't replace, diet, lifestyle, and medical care.
Educational use only, not medical advice or diagnosis. Always interpret lab results with a qualified clinician.