Selenium (Se) is an element that is essential for human health and is found in the same group of the periodic table as oxygen. Selenium was first discovered in 1817 by Jöns J. Berzelius of Sweden. It is found in unrefined foods, especially whole-grain flour , seafood, egg yolk, fish, cereals and products, liver, kidney, garlic and brewer’s yeast. The use of selenium as a therapeutic medicine first started around the 1900s when doctors tried to use selenium to treat cancer in France, Britain, Germany and the United States. Unfortunately, the dosages administered were to high, causing selenium poisoning, and much of the medical profession turned against its medicinal use.
Through the 1930s, evidence showing selenium poisoning of animals arose in America. This was because of the high levels of selenium in cattle feed, and experiments have confirmed that large doses of selenium can be toxic for animals. Evidence that selenium may be an important nutrient for humans started to arise in 1941, and in 1949 it was proved that selenium could prevent the formation of liver tumours in rats. The first breakthrough occurred in 1957, when Dr Klaus Schwartz discovered that liver necrosis in rats could be prevented by kidney extract, which contained selenium. Since then, selenium has become the focus of a large programme of research.
Early experiments revealed that selenium could prevent muscular dystrophy in pigs, sheep, hens and calves. It was at this time that selenium was used as an effective remedy for other livestock diseases and that it was first linked to vitamin E. Vitamin E could replace or accompany selenium in treating these livestock diseases. New Zealand was the first country to make widespread use of the mineral to prevent deficiency problems in domestic animals. This occurred in 1967 and was due to the fact that New Zealand is one of the areas in the world with the lowest levels of soil selenium. In the same year, Finnish vets used selenium to treat muscle disease in domestic animals, and in 1969 veterinary authorities authorized the addition of selenium in animal feeds. Also, since 1984 selenium is added to all artificial fertilizers to increase the selenium intake of agricultural products and hence increase the intake of the humane population.
The Importance of Selenium to Health
In the 1970s researchers discovered that selenium could prevent mutations, which are unusual changes in genetic material that may trigger disease. Such mutations may be entirely harmless or they may prevent basic processes required for life, and these changes may be passed on to the next generation. Then, in 1973, the enzyme glutathione peroxidase was found.
Glutathione peroxidase contains four atoms of selenium in its structure, and it acts against oxygen-free radicals, hydrogen peroxides and fatty acid peroxides, preventing damage to the cell. This finding proved that selenium was very important in preventing animal diseases. Even today, some health practitioners are sceptical about the importance and benefits that selenium can bring in preventing disease.
The first serious cases of selenium deficiency in human arose in the late 1970s in the province of Keshan in China. People there had developed a disease of the heart, similar to ‘mulberry heart’ of cattle, in which the heart muscle degenerated with a subsequent loss of power to pump blood around the body. It arose mainly in young women and children in area with possibly the lowest selenium levels in the world. Without selenium supplementation the disease was fatal. A similar disease affecting the cartilage in the joints, called Kaschin-Beck disease, was found in Russia and China, which again could be prevented and treated with selenium supplements.
