Australian NaturalCare Selenium 150mcg is involved in healthy immune and thyroid function, and supports normal male physiology. Selenium is essential for healthy thyroid and immune system function. It is also required for the healthy development and motility (mobility) of the sperm. Studies show that around one in 10 people in Australia over 71 years don’t obtain the estimated requirements of selenium from their diets, which may lead to suboptimal activity levels of antioxidants such as superoxide dismutase (SOD) and glutathione peroxidase.