In 1817, the Swedish chemist Jöns Jakob Berzelius discovered a previously unknown chemical element and named it after Selene, the goddess of the moon. As a semi-precious metal, selenium occurs in nature in both organic and inorganic compounds. Plants absorb it from the soil, while animals obtain selenium by consuming plants (or other animals).
In a 1957 US publication, physicians Karl Schwarz and Calvin M. Foltz were able to prove that selenium is essential for human and animal organisms. Since then, the essential trace element has gained increasing importance.
It depends on the soil
The concentration of selenium in the soil depends primarily on leaching caused by glacial erosion. Roughly speaking, this means the decomposition of glaciers by meltwater on a glacier bed of rock. Therefore, the selenium content in European soils is significantly lower than in the USA, but on average higher than in China. Researchers assume that it will continue to decline due to climate change. For this reason, selenium in the form of sodium selenite or selenate has been added to animal feed in agriculture for over 20 years.
People who follow a vegetarian or vegan diet do not benefit from this feed additive and are, in fact, more at risk of a selenium deficiency in Europe. Although Brazil nuts contain a lot of selenium, you should be careful when consuming them. Brazil nuts contain natural radioactivity. According to the Federal Office for Radiation Protection, two Brazil nuts per day are harmless to health. According to the DGE (German Nutrition Society in Bonn), the selenium content in 25 grams (about 6 pieces) of Brazil nuts is 63.5 micrograms. Therefore, one should be careful when consuming excessive amounts of Brazil nuts.
Dangers of a selenium deficiency
According to a study, Germans consume an average of 40 micrograms of selenium per day. However, the daily dose considered appropriate by the German Nutrition Society is 60 micrograms for women and as much as 70 for men. Nevertheless, a pronounced selenium deficiency is quite rare in this country among healthy people who have a varied diet. Those most at risk are vegans, people with a certain genetic defect, dialysis patients, people with eating disorders (bulimia or anorexia), and those with diseases that impair nutrient absorption in the intestine.
Symptoms of a selenium deficiency include a significantly increased susceptibility to infection, infertility (in men), and muscle weakness. Hair loss, dry skin, and changes to fingernails and toenails can also be signs of an undersupply. In case of doubt, a blood test at the doctor's office can help determine the selenium level.
An important building block for the organism
Selenium is present in all cells of the body. As a building block of the amino acid selenocysteine, the trace element is a component of around 25 important enzymes. These include glutathione peroxidases, which play an essential role in defending against harmful oxygen radicals. Selenium supports hair and nails and plays a role in thyroid hormones and male sperm. In addition, the microelement is considered to be immunoregulatory. It therefore helps to maintain the body's defenses against foreign pathogens and to prevent excessive immune reactions, such as those common in allergies.
