Selenium is an essential trace element that plays a vital role in the body's metabolism and immunity. It is found naturally in many whole grains, dairy products, meats, fish, shellfish, and eggs. The average person should consume 55 micrograms of selenium daily to avoid a deficiency, which can reduce the body's immunity against diseases and affect fertility. However, consuming more than 400 to 900 micrograms of selenium may be harmful and cause selenium toxicity.
Seleniumis an essential component of several enzymes and proteins, called selenoproteins, which help produce DNA and protect against cell damage and infections.
Most of the body's selenium is stored in muscle tissue, although the thyroid gland contains the highest concentration of selenium due to several selenoproteins that help thyroid function. Selenium deficiency occurs when a person has lower than adequate levels of selenium in their body.Some research suggests that selenium deficiency diseases are related to vitamin E deficiency, so getting both nutrients from a healthy diet can protect against symptoms. Studies are underway to determine if the effects of selenium could help prevent or treat cognitive decline, but scientists believe that getting enough in the diet may help maintain healthy brain function.Those who live in certain parts of Eastern Europe and Africa have soils with low levels of selenium, so populations living in those areas may have compromised immunity as a result. Additionally, people who live in the Northwest, Northeast, Southeast and areas of the Midwest are likely to have the lowest levels of selenium due to the soil in those areas.