Selenium
Essential trace mineral for thyroid function and antioxidant defense.
By Suplagen Team · Updated
What it is
Selenium is an essential trace mineral required for selenoprotein synthesis, including glutathione peroxidase and thyroid deiodinases.
How it works
Component of selenoproteins (glutathione peroxidase, thioredoxin reductase, iodothyronine deiodinases) for antioxidant defense and thyroid hormone conversion.
What the evidence says
Moderate evidence for thyroid support and antioxidant defense; supplementation most beneficial in selenium-deficient areas.
How much to take
The catalog range is 55 to 200 mcg daily, with a 400 mcg ceiling that matters more than most: chronic intake above it causes selenosis, with garlic breath, brittle nails, and fatigue as the tells.
The moderate evidence for thyroid support and antioxidant defense concentrates in people whose diets run low. If yours doesn't, a couple of Brazil nuts covers it without a capsule.
When and how to take it
With food, once daily. Selenomethionine is the well-absorbed form to look for.
Count all sources. A multivitamin, a thyroid formula, and a standalone selenium capsule can cross the ceiling together, which is exactly the doubling our ceilings article warns about.
Who should skip it
Safe in pregnancy, with no contraindicated conditions. Two interactions: statins (mild) and cisplatin chemotherapy (moderate). Anyone in cancer treatment should clear every supplement with their oncology team, selenium included.
Safety Notes
- UL is 400 mcg/day. Chronic excess causes selenosis (garlic breath, brittle nails, fatigue). Brazil nuts are rich in selenium.
- statins: High-dose selenium may reduce statin efficacy; stay within recommended range.
- chemotherapy (cisplatin): Selenium may alter drug effects; consult oncologist.
Common questions
How much selenium should I take per day?
55 to 200 mcg, with 400 mcg as the hard ceiling. If your diet includes Brazil nuts or seafood regularly, you may not need a supplement at all.
What form of selenium is best?
Selenomethionine, which the catalog notes is well absorbed. Take it with food.
What happens if you take too much selenium?
Selenosis: garlic breath, brittle nails, and fatigue. It comes from chronic intake above 400 mcg, usually from stacking several products that each contain some.