Lifestream Selenium Natural 90 CapsLifestream Selenium Natural 90 Caps About Vitamins. co. nz Lifestream Selenium Natural Selenium, like most trace elements and minerals, is not evenly distributed in the worlds soil. Many parts of New Zealand and Australian soils are known to be selenium deficient, therefore our food may be lacking this essential trace element. Selenium is necessary for antioxidant protection, and optimum immune and thyroid function. It also plays a role in fertility