Selenium
The mineral selenium is an essential trace element for humans that protects cells from oxidative stress. Selenium must be ingested with food; the human organism cannot produce it itself.
Selenium – an indispensable trace element
What is selenium?
Selenium is a grey mineral in its most stable form. It occurs in sulfurous ores together with metals such as gold or copper. These are inorganic forms of minerals. The organic forms of selenium, predominantly selenium methionine, which is found in yeasts and plants, are significant for humans and their health. Selenium is called an essential trace element because it is vital for humans and cannot be formed by the human body.
Cell protection against oxidative stress with selenium
Selenium is a radical scavenger. Free radicals stress cells oxidatively. Free radicals are aggressive oxygen particles that are resistant to binding. They are looking for chemical binding partners in the human body and react with cells. This damages the cell. The process is similar to the rust formation of metals. This also leads to oxidation. Free radicals are associated with diseases and with the aging process.
Selenium can intercept free radicals and, by reacting with them, render them harmless to the cells. Other radical scavengers – often referred to as antioxidants – include vitamin C, vitamin E, zinc and vitamin B2
EFSA confirms cell protection against oxidative stress in these micronutrients. Certain secondary plant substances are also referred to as radical scavengers. It is with these substances that plants protect themselves from environmental influences. This includes, for example, flavonoids and carotenoids. However, clear scientific data on the subject is still missing. An exception applies to olive polyphenols, which contribute to the protection of blood fats against oxidative stress from the point of view of the EFSA.
What role does selenium play in the human body?
The European Food and Drug Administration EFSA certifies these effects:
Selenium contributes to normal sperm formation.
Selenium helps maintain normal hair and nails.
Selenium contributes to the normal functioning of the immune system.
Selenium contributes to normal thyroid function.
Selenium contributes to the protection of cells from oxidative stress.
Cell protection against oxidative stress with selenium
Selenium is a radical scavenger. Free radicals stress cells oxidatively. Free radicals are aggressive oxygen particles that are resistant to binding. They are looking for chemical binding partners in the human body and react with cells. This damages the cell. The process is similar to the rust formation of metals. This also leads to oxidation. Free radicals are associated with diseases and with the aging process.
Selenium can intercept free radicals and, by reacting with them, render them harmless to the cells. Other radical scavengers – often referred to as antioxidants – include vitamin C, vitamin E, zinc and vitamin B2
EFSA confirms cell protection against oxidative stress in these micronutrients. Certain secondary plant substances are also referred to as radical scavengers. It is with these substances that plants protect themselves from environmental influences. This includes, for example, flavonoids and carotenoids. However, clear scientific data on the subject is still missing. An exception applies to olive polyphenols, which contribute to the protection of blood fats against oxidative stress from the point of view of the EFSA.
Free radicals and selenium
Processes in which free radicals occur:
Stress
Metabolism
Lack of sleep
Smoking
UV radiation
Diseases
Taking medication
Chemotherapy
Toxins
The physiological significance of selenium in the human body
Selenium is used, among other things, in the amino acid selenocysteine. This protein component is part of certain enzymes, which are called selenium-dependent. Enzymes act as a catalyst. This means that they facilitate certain reactions between substances in the body or make them possible. For example, selenium activates the extremely important thyroid hormone T4 via a selenium-dependent enzyme.
Selenomethionine is also incorporated into other amino acids. It is considered a connection that saves selenium until it is needed.
What foods contain selenium?
The selenium content of plant-based food depends significantly on how much selenium is present in the soil on which a crop grows. Like many other European countries, Germany is seen as poor in selenium when it comes to soil quality. Therefore, livestock is often fed selenium so that we can absorb the trace element more effectively via animal products.
The need for selenium in adolescents and adults is assumed to be approximately 60 to 70 μg per day.
Selenium in food
These foods are particularly rich in selenium (depending on the soil quality, environment and feed):
Nuts
Tuna fish
Prawns
Eggs
Meat
What are the consequences of a selenium deficiency?
Different cases must be differentiated for potential selenium deficiency.
Less selenium may be absorbed than recommended in the case of an unbalanced diet. Here, food supplements can be a way to supplement the selenium content in food.
In addition, real selenium deficiency diseases are known. They are generally not (only) due to a selenium deficiency in the human body, but rather to the fact that the selenium deficiency changes viruses so that they become particularly aggressive.
What are the consequences of an excessive intake of selenium?
Absorption of selenium in too high doses can lead to selenosis with various symptoms such as hair loss, heart disorders, nausea, and other symptoms. However, this is mainly about the intake of highly toxic selenium in an industrial context. In particular, selenium should not be inhaled. It is not certain from which doses negative consequences are to be expected. Here, the information varies between 400 and 3000 μg per day.
Conclusion
Selenium is a vital trace element. In areas of selenium deficiency such as Germany, nutritional supplements can be useful. However, the dosage is decisive. Excessive intake of selenium should be avoided. Various medical measuring procedures are available for the selenium content in the blood, which can provide information about a potential selenium deficiency. The optimal values in whole blood are 121 to 168 μg selenium per liter of whole blood.
