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Selenium is a trace element that plants get from the earth and we feed ourselves through food. People need selenium: it strengthens the immune system and is necessary to build up proteins. Now, however, the amount of selenium in the soil is falling, worldwide. The cause is global warming.
If we ingest too little selenium, the immune system can no longer work effectively and the body can no longer produce the necessary proteins. Heart failure or a diseased heart muscle are possible consequences.For example, there is a risk of cancer in the event of deficiency symptoms: selenium can protect the liver.
Oxygen, carbon and clay
How much selenium is formed depends, among other things, on the oxygen, carbon and clay in the soil, and also on the pH value. Northern European countries such as Denmark, Finland, Scotland and Germany are poor in selenium.
Swiss researchers from the Swiss Federal Institute for Water Supply, Wastewater Treatment and Water Protection have now examined the global amount of selenium using 33,241 soil samples taken between 1994 and 2016.
The climate decides
They came to the conclusion that the relationship between climate and soil is crucial for the concentration of selenium. Precipitation and evaporation are particularly important. A lot of rain washes away the soil and thus the selenium.
Wet floors have little oxygen
However, the equation of a lot of rain and a little of selenium is not true, because soil soaked in rain contains less oxygen and a lower pH value, i.e. a certain degree of acidification, and so the selenium remains better bound to the soil.
Where is the most selenium?
The study found that little to medium precipitation and a lot of clay in the soil are ideal for a high concentration of selenium.
The selenium concentration drops
The study designs the following scenario: Global warming increases the concentration of the substance in certain regions of India, China, Australia and Africa. However, the concentration is falling worldwide.
Selenium loss of nine percent
By the end of this century, the amount of selenium in around 66% of all agricultural areas will decrease by nine percent. Europe, South Africa, the western United States and southern South America are most severely affected. According to the study, there are already a billion people suffering from selenium deficiency.
What to do?
The researchers suggest using selenium-containing fertilizer and adding selenium to animal feed. (Dr. Utz Anhalt)
Source: (Proceedings of the National Academy of Sciences, 2017; doi: 10.1073 / pnas.1611576114)