What is the primary role of selenium in the diet?

Selenium plays a crucial role in the diet primarily as an antioxidant and is important for thyroid function. This essential trace mineral is a key component of several enzymes and proteins known as selenoproteins, which are involved in antioxidant defense systems that help protect the body from oxidative stress. Oxidative stress can lead to cellular damage, and selenium's antioxidant properties assist in neutralizing free radicals, thereby contributing to overall health.

In addition to its antioxidant capabilities, selenium is vital for thyroid hormone metabolism. It is necessary for the conversion of the inactive thyroid hormone (T4) into its active form (T3), which is essential for regulating metabolism, growth, and development. A deficiency in selenium can lead to thyroid dysfunction, among other health issues.

The other options do not accurately describe the primary role of selenium. Enhancing flavor in foods relates more to other compounds, while preservatives are substances that prolong shelf life but do not include selenium in this function. Dietary fiber is found in plant foods and is important for digestive health, but selenium does not provide fiber.