• Selenium is required for the proper activity of a group of enzymes called glutathione peroxidases. These enzymes play a key role in the body's detoxification system and they also provide protection against oxidative stress. (Oxidative stress is physiological circumstance in which there is excessive risk of oxygen-related damage to the body.) Of the eight known glutathione peroxidase enzymes, five of them require selenium.
• In addition to the activity of glutathione peroxidase, selenium-containing enzymes are involved in recycling of vitamin C from its spent form back to its active one, allowing for greater antioxidant protection.
• Support Normal Thyroid Function.
• A selenium-containing enzyme is responsible for transforming a less active thyroid hormone called T4 into the more active T3. As you'll see below in the Relationship with Other Nutrients section, selenium and iodine work together to keep thyroid function strong and consistent.
• Like the antioxidant protection issue, this is not just an esoteric concern. Researchers have been able to induce problems with the thyroid gland in just two months of a low-selenium diet