Selenium is an essential trace mineral which enters the food chain through plants and plays an important role in many functions in the body. It has a key role in thyroxine metabolism as well as an invaluable nutrient in reproductive health. In conjunction with Vitamin E, selenium is also needed for making Coenzyme Q10 . Selenium is stored in the red blood cells, liver, spleen and the heart. Researchers from the University of Chicago have recently found a gene type that may require elevated levels of selenium to retain cancer protection. Cancer research(2003:63:3347)
Selenium can be found in foods such as liver, oily fish, cereals, whole grains, fruits, brazil nuts, mushrooms ,vegetables and dairy products. There is wide variation as to the selenium content of these foods, as this is dependent on the amount of selenium in the soil where the food is grown.
Selenium is an "antioxidant" i.e. it helps protect cells and tissues from damage by "oxidants" - especially "free radicals". Free radicals are molecules produced by normal biological reactions, which are volatile and potentially toxic. Selenium is able to remove free radicals from the body before they can cause damage to cells or tissues.
Falling dietary levels of Selenium in recent years are largely because we now tend to eat bread made with varieties of wheat that are low in this key mineral. This means, that an ordinary healthy diet may not be enough on its own to provide the intake of selenium our bodies need.
There is no European Adult Recommended Daily Allowance (RDA) for selenium but it is believed that most people eat between 25 - 130 micrograms per day.
Selenium deficiency is very rare, although marginal deficiency may occur in parts of the world where the soil is poor in selenium and access to a range of food is problematic. There are no specific symptoms of deficiency, but it can bring on certain conditions, for example Keshan's disease ( a degenerative heart condition) and subfertility.
Like selenium, vitamins A, C and E are vital for good health and are antioxidants. Vitamin A is essential for growth, vision in dim light and the maintenance of mucous tissue.
Vitamin C helps maintain healthy connective tissues and cell walls.
Vitamin E stabilises cell membranes, protecting their unsaturated fatty acids from oxidation.