What is selenium?
Selenium is an essential – vital – trace element. Since the human organism cannot produce selenium itself, it must be supplied regularly through the diet. It is absorbed from food into the blood in the small intestine and stored primarily in the skeletal muscles. However, traces of selenium are also found in the kidneys, heart and liver, as well as in the blood and brain. The substance is excreted in the urine.
Selenium: Supply status
The supply status of the population with selenium in Europe is recorded on a pan-European level. Although Europe’s soils contain little selenium compared with those of the USA, for example, the selenium supply of Europeans is considered to be largely assured.
However, an undersupply can occur in regions with particularly selenium-poor soils. Vegetable foods grown there contain correspondingly little selenium. In the case of a purely vegetarian or vegan diet with predominantly regional products, a selenium deficiency can then arise. Vegetarians and vegans should therefore be sure to regularly consume plant foods that have been shown to contain high levels of selenium. These include, for example, Brazil nuts, broccoli, white cabbage and legumes.
What are the functions of selenium in the body?
In the form of the amino acid seleocysteine, selenium is an important building block of numerous enzymes and thus involved in many important metabolic processes. Thus, selenium has a supporting effect in the following areas:
- immune defense: selenium is required by the immune system in the formation of defense cells.
- @ antioxidative processes: In this process, cell-damaging free radicals are bound. These are aggressive oxygen compounds that are formed in the body in the course of normal metabolic processes as well as, for example, through UV radiation or nicotine.
- Sperm production
- Formation of the thyroid hormones thyroxine (T4) and triiodothyorine (T3)
- Binding of heavy metals in the body (e.g. lead, cadmium, mercury)
Physicians have long suspected that selenium may also protect against cardiovascular disease and cancer. However, this hypothesis has been disproved in large-scale studies or, in the case of cancer prevention, has not yet been confirmed.
What is the daily requirement of selenium?
|
Age |
Male |
female |
|
0 to 4 months |
10 µg/day |
|
|
4 months to 4 years |
15 µg/day |
|
|
4 to 7 years |
20 µg/day |
|
|
7 to 10 years |
30 µg/day |
|
|
10 to 13 years |
45 µg/day |
|
|
13 to 15 years |
60 µg/day |
|
|
from 15 years |
70 µg/day |
60 µg/day |
Pregnant women are also recommended 60 µg of selenium per day, and breastfeeding women 75 µg/day.
Selenium – foods with high content
A balanced diet normally provides the daily selenium requirement estimated by the German, Austrian and Swiss Societies for Nutrition. For vegetarians, vegans, people with chronic intestinal diseases, and those who eat an extremely unbalanced diet, selenium-containing dietary supplements may be useful.
You can find out which foods have a high selenium content in the article Selenium foods.
How does a selenium deficiency manifest itself?
People who have too little selenium in their blood may develop immune deficiency or impaired muscle function, for example. In addition, a deficiency of selenium impairs the thyroid gland in its function.
Read more about the typical signs of a selenium deficiency in the article Selenium Deficiency.
How does an excess of selenium manifest itself?
A permanent overdose with selenium has serious side effects and can cause a so-called selenosis with the following symptoms:
- gastrointestinal complaints such as nausea and diarrhea
- Joint pain
- visual disturbances
- Memory problems
- Skin and dental problems
Too little selenium can also cause hair loss and brittle nails.
A drastic overdose of several grams of selenium can even cause ventricular fibrillation, heart failure and ultimately death.