Selenium contributes to the maintenance of normal hair and nails, the normal function of the immune system, normal thyroid function and for the protection of cells from oxidative stress. This 'oxidative stress' appears to be a major factor in many human diseases. Selenium also contributes to normal spermatogenesis (the creation of sperm). Intensive farming has led to greatly reduced levels of this important mineral in our foods. This supplement presents selenium in the preferred selenomethionine form.