mineral · for frequent colds
Selenium
Your immune cells need selenium to work properly and to make antibodies.
Say that in clinical terms
Selenoproteins enhance immune cell function and antibody production. Glutathione peroxidase reduces oxidative stress during infection.
How strong is the research?
1 paper read, 1 supporting.
Tested as: Sodium Selenite
Who was studied: The immune studies are in people who were selenium-deficient, elderly, or immunocompromised.
A proper search found trials of this compound, but not in the form named here — Sodium Selenite. Evidence for one form is not evidence for another.
How much to take
daily
55–100 mcg
Upper limit 400 mcg/day. Take with vitamin E for enhanced antioxidant activity.
Before you take it
- NIH ODS Tolerable Upper Intake Level (UL) for selenium is 400 mcg/day for all adults (ages 14+); EFSA (2023) set a more conservative UL of 255 mcg/day for all adults based on evidence linking chronic excess intake to hair loss and nail changes.
- The primary clinical signs of chronically high selenium intake (selenosis) are hair loss and nail brittleness or loss; NIH ODS explicitly names these as the most common manifestations of selenium toxicity, not deficiency.
- Average US dietary selenium intake is approximately 100–150 mcg/day; supplemental doses of 100–200 mcg/day may approach or exceed the EFSA UL (255 mcg/day) in individuals with higher dietary selenium from food or geography, without the user being aware.
- Individuals in high-selenium geographic regions (parts of the US Great Plains — South Dakota, Nebraska, Wyoming) may have dietary intakes near or above the NIH UL before any supplementation is added.
- Drug interaction: cisplatin and platinum-based chemotherapy agents reduce selenium concentrations in hair and serum; selenium supplementation during chemotherapy may affect cisplatin efficacy; patients on these agents must consult their oncologist before supplementing.
- Selenium form substantially affects bioavailability and tissue retention: selenomethionine (organic) is retained longer and accumulates more in tissues than sodium selenite (inorganic) or selenium-enriched yeast; the same supplemental dose carries meaningfully different toxicity profiles depending on the form.
- In thyroid patients on levothyroxine, selenium is a cofactor for iodothyronine deiodinase enzymes that convert T4 to active T3; supplementation may alter thyroid hormone metabolism and should be disclosed to the prescribing clinician.
- Selenium supplementation above the RDA (55 mcg/day) is not recommended during pregnancy without confirmed deficiency; excessive selenium is teratogenic in animal models.
- A 2008 US outbreak documented 201 individuals developing alopecia, nail changes, and neurological symptoms from a commercial selenium-containing supplement; the product contained approximately 200 times its labeled selenium amount, demonstrating the real-world toxicity risk from over-the-counter selenium products.
When to take it
Best taken: with food
What we make of it
The citation does not resolve and appears to be wrong or invented.
The detail
The identifier we stored does not lead to the paper described — it redirects somewhere inconsistent with the journal named. The citation cannot be trusted and needs replacing.