Selenium plays a critical role in metabolism and thyroid function and helps protect your body from damage caused by oxidative stress. Selenium may help boost your immune system, slow age-related mental decline, and even reduce your risk of heart diseases. Iodine is needed by the body to make thyroid hormones. These hormones control the body's metabolism and many other important functions. The body also needs thyroid hormones for proper bone and brain development during pregnancy and infancy. Molybdenum is a mineral that you need to stay healthy. Your body uses molybdenum to process proteins and genetic material like DNA.Molybdenum also helps break down drugs and toxic substances that enter the body.