Check before you startThis one has documented interactions with medication classes where the consequences are serious. If you take any prescription medicine, run it past a pharmacist before starting.
Evidence strength
72/100Strong
WEAKLIMITEDMODERATESTRONGVERY STRONG
What the evidence supports: correcting deficiency in low-soil regions.
This scores how well-supported the claim above is — not how much benefit you personally would get. A high score on a narrow claim does not extend to everything the product is marketed for.
How long to take it
Ongoing only in genuinely low-selenium regions. Otherwise unnecessary.
Who it's actually for
People in low-selenium soil areas, and some thyroid conditions under supervision.
Safe upper limit
Unverified
400 mcg per day
The gap between adequate and toxic is narrow. Excess causes hair loss, brittle nails, garlic breath, and nerve damage.