Selenium

Selenium is regulatory, despite its small quantity.

It functions as a cofactor in antioxidant enzymes
and plays a role in the conversion of thyroid hormones.

At a high level, evaluation comes down to three signals:

• Form (selenite, selenomethionine, etc.) — differences in metabolism and retention
• Dose range — narrow margin between sufficiency and excess
• Functional context — relevance to antioxidant systems and thyroid regulation

Selenium is required in small amounts.

Its effects are not linear with dose.

Both deficiency and excess can disrupt function.
Balance defines its role.