Selenium is also important in the activation of thyroid hormone and helps to decrease heavy metals like lead, mercury, cadmium and aluminum. Mild deficiency of selenium results in decreased immune function and and increased risk of cancer. More pronounced deficiency causes Keshan disease, a severe heart disease of children and young women. Selenium deficiency has also been linked to Kashin-Beck disease, an arthritic condition and to heart disturbances and muscle weakness.
Deficiency occurs with malnutrition and in areas where the soil has very low selenium levels.
Selenium toxicity can occur with intake of as little as 900 mcg daily and is characterized by depression, nervousness, irritability, nausea, vomiting, skin rash, garlic smelling breath and hair and fingernail loss. Back to the Index. Forms Selenomethionine Back to the Index. Food Sources Wheat germ, brazil nuts and nutritional yeast are all high in selenium. Whole grains and seafood are good sources.