Selenium is an essential trace element, but selenium deficiency is rare. Elevated selenium levels should also be avoided. What are the effects of selenium excess or deficiency? You can read about that here.
Selenium: Deficiency symptoms
In many regions of Europe, including Germany, soils contain little selenium – due in part to acid rain polluted with sulfur dioxide, as well as fertilizers containing sulfur. Sulfur is then absorbed by plants instead of selenium. Because of the large differences in the selenium content of soils, the selenium content in crops also varies greatly. Animal proteins are therefore usually better sources of selenium than plant foods in selenium-poor growing regions. This is because the trace element is often added to cattle feed – partly because it makes the animals less susceptible to disease. Some scientists classify Germany as a selenium deficient area, because often the actual selenium intake – for adults on average 60 to 70 μg /day – falls short of the recommendation of the German Nutrition Society (DGE).
Selenium deficiency: causes and affected individuals
Selenium deficiency can occur for a variety of reasons:
- Affected by a selenium deficiency are in many cases people who, for one, take in little selenium with their diet: These include people who eat only vegetable protein, poorly nourished elderly people, people with an unbalanced diet, tube-fed patients and dialysis patients. Alcohol abuse can also lead to a deficiency of selenium. Nevertheless, a selenium deficiency due to insufficient intake in Germany is rather rare.
- Also, a selenium deficiency can occur if increased selenium is excreted: This can happen with prolonged diarrhea, but also through the urine in diabetes mellitus or severe kidney disease.
- Gastrointestinal diseases (for example, chronic inflammatory bowel diseases such as ulcerative colitis) can lead to impaired selenium absorption.
- An increased selenium requirement may exist during pregnancy, heavy menstrual bleeding and during breastfeeding. Also in cancer, the body “consumes” more selenium.
Consequences of deficiency of selenium
The consequences of selenium deficiency have not yet been definitively researched. In extreme selenium deficiency areas of China and central Russia, the most severe heart muscle diseases and diseases of the joints have been observed. However, it is still not clear whether these so-called Keshan disease and Kashin-Beck disease are actually consequences of selenium deficiency or whether other triggers are present. Recent studies also suggest a connection between low selenium levels and high blood pressure, lipid metabolism disorders and the development of arteriosclerosis. There is also evidence that selenium deficiency can affect fertility: Women who suffered miscarriages had extremely low blood levels of the trace element. In men with a selenium deficiency, sperm maturation and motility may be impaired. In addition, the immune system and muscle function may be impaired.
Selenium excess: elevated levels of selenium in the blood due to overdose
Selenium has toxic effects in higher concentrations. Normally, therefore, the body excretes excess selenium in the urine. However, if larger amounts are regularly taken over a longer period of time, for example via dietary supplements, symptoms may occur. Possible consequences are fatigue, nausea, diarrhea, joint pain and nervous disorders. In the further course of this so-called selenosis, hair loss, liver damage, cardiac muscle weakness and a typical smell of garlic on the breath may occur. Acute selenium poisoning can lead to death. According to the recommendations of the European Food Safety Authority (EFSA), adults should therefore not exceed a daily intake of 300 µg of selenium. For children, a maximum daily intake of 60 to 250 µg applies, depending on body weight.
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Online information from the German Nutrition Society. (DGE): selenium. (Accessed 10/2020)
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Online information of the German Society for Nutrition e. V. (DGE): Selected questions and answers about selenium. (retrieval: 10/2020)
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Tan, H. W. et al. (2018): Selenium species: current status and potentials in cancer prevention and therapy. In: International Journal of Molecular Sciences, Vol. 20(1).
