Selenium is a mineral normally found in soil, water and some foods. However much of New Zealand's soil and water is low in selenium and while people only need a very small amount, selenium plays a key role in the metabolism.

Seleniums main use is that of its antioxidant properties as antioxidants protect cells from free-radical damage. Selenium supplements may support the reduction of prostate cancer.

Selenium has also been studied for the treatment of dozens of conditions. They range from asthma to arthritis to dandruff to infertility. However, the results have been inconclusive.

Please be aware that too much selenium can be harmful and for adults the general consensus is that 400mg is the upper limit.