High-Potency Selenium – Provides 200 mcg of L-Selenomethionine to support antioxidant protection and healthy thyroid function. NOW Selenium 200 mcg – Provides a highly bioavailable form of the essential trace mineral selenium, delivered as L-selenomethionine. Naturally found in foods like Brazil nuts, seafood, organ meats, and wheat germ. And plays a key role in antioxidant defense, immune support, and healthy thyroid hormone metabolism.