Selenium is an essential mineral that is important for many bodily functions, including reproduction, thyroid hormone metabolism, and protection against oxidative damage.

The recommended daily intake of selenium varies depending on age, sex, and other factors, but ranges from 15 to 55 micrograms per day.

Selenium deficiency is rare in the United States, but can occur in people with certain medical conditions or who are receiving certain medical treatments. However, excessive intake of selenium can also be harmful and can cause symptoms such as hair loss, nail brittleness, and gastrointestinal upset.