Selenium is a natural antioxidant useful to preserve the elasticity of tissues by delaying the oxidation of polyunsaturated fatty acids, which can cause a solidification of tissue proteins.
The content of Selenium in food depends on the extent to which it is present in the soil, that is directly in the case of food plants or indirectly as in animal products whose levels of Selenium derive from their food. Selenium is found in bran and germ of cereals, in vegetables such as broccoli, onions, tomatoes and tuna.
The liver and kidneys contain four to five times the amount of Selenium contained in the muscles and other tissues. Selenium is normally eliminated through the urine; its presence in the stool is an indication of improper absorption. The recommended dose of Selenium for adults is extremely low and ranges from 50 <100 micrograms per day.