The body needs selenium for normal growth and health.
Selenium is needed for certain enzymes that help with normal body functions.
Lack of selenium may lead to changes in fingernails, muscle weakness, and heart problems. Selenium deficiency in the United States is rare. Selenium deficiency is a problem in areas of the world where the soil contains little selenium. Although selenium is being used to prevent certain types of cancer, there is not enough information to show that this is effective. Injectable selenium is given by or under the supervision of a health care professional.