Ernährung

Selenium: an essential mineral for immune function and the nervous system

Written by

Anna Roell
18 July, 2023

All HOMED-IQ content is reviewed by medical specialists

Selen ist ein essenzielles Spurenelement, das für viele Vorgänge in unserem Körper wichtig ist, unter anderem für die Unterstützung des Immunsystems und den Schutz vor oxidativem Stress. Doch was passiert, wenn unser Körper nicht ausreichend mit Selen versorgt ist? Und in welchen Lebensmitteln ist Selen enthalten? In diesem Artikel gehen wir auf die Bedeutung von Selen ein und erklären, was passiert, wenn unser Körper entweder zu wenig oder zu viel davon hat.

What is selenium?

Selen ist ein essentielles Spurenelement, das heißt, es ist ein Mineral, das unser Körper in sehr geringen Mengen benötigt, aber trotzdem für seine ordnungsgemäße Funktion unerlässlich ist. Wir können es nicht selbst produzieren und müssen es daher über unsere Ernährung aufnehmen (Harvard Health, 2023). 

What is the function of selenium in the body?

Selenium plays a critical role in many processes in the body. These factors can include:

  1. Antioxidative Wirkung: Selen ist ein wichtiger Bestandteil der Enzyme, die freie Radikale neutralisieren. Freie Radikale können die Zellen schädigen, wenn sie sich im Körper ansammeln. Dieser Zustand wird als oxidativer Stress bezeichnet. Durch die Neutralisierung der freien Radikale hilft Selen, oxidativen Stress zu verringern und Zellschäden zu verhindern.
  2. Schilddrüsenfunktion: Selen spielt auch eine wichtige Rolle in der Schilddrüse. Die Schilddrüse ist wichtig für die Regulierung des Stoffwechsels und der Körpertemperatur spielt. Sie tut dies durch die Produktion von Schilddrüsenhormonen, insbesondere von Triiodthyronin (T3) und Thyroxin (T4). Selen ist ein integraler Bestandteil mehrerer Enzyme, die wichtig für die Umwandlung des inaktiven Schilddrüsenhormons T4 in das aktive Schilddrüsenhormon T3 und somit die Funktion der Hormone ermöglichen. 
  3. Immune system: Selenium also supports the function of the immune system. It is involved in the production and function of immune cells and is associated with an enhanced immune response. Conversely, selenium deficiency is associated with a slower immune response.
  4. Nervensystem: Selen spielt eine wichtige Rolle bei verschiedenen Aspekten der Gehirnfunktion und der Gesundheit des Nervensystems. Einige spezifische selenhaltige Proteine, so genannte Selenoproteine, haben verschiedene Funktionen, darunter die Regulierung von Entzündungsreaktionen im Gehirn und die Unterstützung der Gehirnentwicklung.

Source: Rayman, 2012

Wie viel Selen sollte man täglich zu sich nehmen?

Adults over 19 years of age are recommended to consume 55 micrograms of selenium per day. Pregnant women should consume 60 micrograms, while breastfeeding women should consume 70 micrograms per day.

However, it is important to note that selenium requirements can depend on many factors, including overall health and individual metabolism. If you have questions about your specific selenium needs, consult your doctor (NIH, 2021).

What foods contain selenium?

Most people obtain enough selenium through their diet, and a variety of foods can serve as a source of selenium. It should be noted that the selenium content in plants and animals is highly dependent on the amount of selenium in the soil on which they are grown or fed. Examples of foods high in selenium include:

  • Fish and seafood: Fish and seafood are excellent sources of selenium. Tuna, salmon, cod, shrimp and oysters are among the best sources of this important mineral.
  • Meat and poultry: Animal products such as beef, chicken, turkey and pork also contain considerable amounts of selenium. However, the exact amount can vary depending on the type of animal, its diet, and its living conditions.
  • Eier: Eier sind eine weitere gute Quelle für Selen, insbesondere das Eigelb.
  • Whole grain products: Whole grain bread, brown rice and oatmeal also contain selenium. Again, the amount may vary depending on the soil in which they are grown.
  • Nüsse und Samen: Besonders die Paranuss ist bekannt für ihren hohen Selengehalt. In einer einzelnen Paranuss sind etwa 68-91 mcg enthalten, sodass  schon ein oder zwei Nüsse Ihren täglichen Selenbedarf decken. Aber auch Sonnenblumenkerne und Leinsamen enthalten Selen.
  • Legumes: Beans, lentils and chickpeas are also sources of selenium.

Source: Cleveland Clinic, 2023

What is a selenium deficiency?

A selenium deficiency occurs when the body does not get enough selenium to function properly. This can lead to a number of health problems, including weakening of the immune system, cardiovascular disease, and problems with the thyroid gland (Kieliszek & Błażejak, 2013).

Who is at increased risk for selenium deficiency?

Selenium deficiency is relatively rare in most parts of the world, but can occur in certain populations that are at increased risk. Examples of foods high in selenium include:

  • People with autoimmune diseases: Some autoimmune diseases can interfere with the absorption of selenium from the diet or lead to an increased need for this mineral. In people with celiac disease, the ingestion of gluten damages the intestinal lining and can impair the absorption of nutrients, which might reduce an individual’s ability to absorb adequate selenium. Crohn’s disease, an autoimmune condition that causes chronic inflammation of the digestive tract, may also cause impaired absorption of nutrients including selenium.
  • Menschen mit weiteren Erkrankungen: Der Selenspiegel ist bei Menschen, die sich einer Nierendialyse infolge bestimmter Nierenerkrankungen unterziehen, deutlich niedriger als bei gesunden Personen. Durch die Hämodialyse wird ein Teil des Selens aus dem Blut entfernt. Auch bei HIV-Infizierten sind die Selenspiegel häufig niedrig, was möglicherweise auf eine unzureichende Aufnahme, übermäßige Verluste durch Durchfall und Malabsorption zurückzuführen ist.
  • People living in selenium-deficient regions: Selenium levels in foods can vary widely, depending on the selenium content of the soil in which plants are grown or animals are fed. In some parts of the world, such as certain regions of China and Europe, selenium levels in the soil are low, which may mean that people living in these regions do not get enough selenium through their diets.

Source: NIH, 2021

Welche Symptome weisen auf einen Selenmangel hin?

Symptoms of selenium deficiency can vary in severity and are often nonspecific, making them difficult to diagnose. Common symptoms include:

If the deficiency is severe or persistent, more specific symptoms may occur, such as Keshan disease (a specific heart disease) or Kashin-Beck disease (a type of arthritis).

It is important to note that many of these symptoms can also occur with other diseases or nutrient deficiencies. Therefore, it is difficult to diagnose a selenium deficiency based on symptoms alone. If you suspect you may have a selenium deficiency, consult a doctor for follow-up testing.

Quelle: Olsen, 2023

Mit welchen anderen Krankheiten wird Selen in Verbindung gebracht?

In addition to its importance in the immune system and thyroid function, the role of selenium in the prevention and treatment of various diseases is being studied. Some research suggests that low levels of selenium in the blood may be associated with an increased risk of cardiovascular disease. Because blood selenium concentrations decline with age, low or deficient selenium concentrations may be associated with age-related declines in brain function. While further research in this area is needed, getting adequate selenium is a good idea in supporting your overall health (NIH, 2021).

Was passiert bei einer Überdosierung von Selen?

Elevated selenium levels, known as selenosis, can be caused by excessive intake of selenium, often through consuming too many supplements or brazil nuts, which contain large amounts of selenium. Symptoms can vary depending on the severity of selenosis, but may include:

Serious health consequences can occur if selenium levels remain high for a long period of time, including severe neurological and gastrointestinal problems, heart problems, and even death in extreme cases. It is important to seek immediate medical attention if selenosis is suspected.

In order to prevent selenosis, supplements containing selenium should be taken with caution and under the guidance of a healthcare provider (Kieliszek & Błażejak, 2013; Harvard Health, 2023). It is also important to only consume foods that are high in selenium in moderation, such as brazil nuts.

Wie wird ein Selenmangel oder -überdosierung diagnostiziert?

Die Diagnose eines hohen oder niedrigen Selenspiegels basiert normalerweise auf einer Kombination aus Symptomen und Laboruntersuchungen. Die Symptome allein sind oft unspezifisch und können auf eine Vielzahl von gesundheitlichen Zuständen hinweisen, weshalb Blutuntersuchungen entscheidend sind. Bei Verdacht auf einen Selenmangel oder eine Selenvergiftung kann ein Arzt eine Blutuntersuchung anordnen, um den Selenspiegel im Blut zu messen. Es sollte beachtet werden, dass diese Tests nicht immer eindeutig sind, da der Selenspiegel im Blut auch durch Faktoren wie den kürzlich erfolgten Verzehr von selenreichen Lebensmitteln beeinflusst werden kann. Es können auch Haar- oder Nagelproben genommen werden, um den Selenstatus über einen längeren Zeitraum zu beurteilen (Olsen, 2023).

Would you like to check in on your own health from home?

Nutritional deficiencies often cause non-specific symptoms, making it difficult to identify the root cause. Homed-IQ’s blood tests can provide insight into your nutritional status from the comfort of home. As selenium is essential for the synthesis of thyroid hormones, Homed-IQ’s Thyroid Test can be used to assess thyroid function without visiting a doctor’s office. If you would like to test the level of other essential vitamins in your body, Homed-IQ’s Vitamin Deficiency Test can provide valuable insight into your overall nutritional status. With laboratory-certified test results from a simple finger prick, Homed-IQ’s home tests make it possible to proactively take care of one’s health and take action when needed.

Welche Therapiemöglichkeiten gibt es bei einem Selenmangel oder -überdosierung?

In the case of selenium deficiency, a doctor may recommend making changes to your diet to include more selenium rich foods. In the case of a severe deficiency or if the person has difficulty getting enough selenium through their diet, a doctor may prescribe selenium supplements. If the cause of selenium deficiency is due to another medical condition, the underlying cause may need to be treated first.

In cases of selenium poisoning (selenosis), the primary treatment is to immediately reduce or stop the intake of selenium. In severe cases, medical detoxification may be necessary.

Summary

Selenium is a vital nutrient that is essential for the immune system, thyroid function, and nervous system health. A deficiency can cause various symptoms, including fatigue, a weakened immune system, and cognitive problems. At the same time, excessive intake of selenium can lead to health problems known as selenosis. It is important to maintain adequate selenium levels through a balanced diet to promote health and well-being.

Referenzen

Benefits of Selenium. (2023, May 31). Cleveland Clinic Health Essentials. Retrieved July 6, 2023, from https://health.clevelandclinic.org/selenium-benefits/

Kieliszek, M., & Blazejak, S. (2016). Current Knowledge on the Importance of Selenium in Food for Living Organisms: A Review. Molecules, 21(5), 609. https://www.mdpi.com/1420-3049/21/5/609

O’Carroll, D. (n.d.). Selenium Deficiency: Symptoms, Causes, and Treatment. Healthline. Retrieved July 6, 2023, from https://www.healthline.com/health/selenium-deficiency#symptoms

Rayman, M. P. (2012). Selenium and human health. The Lancet, 379(9822), 1256-1268. https://www.sciencedirect.com/science/article/pii/S0140673611614529?via%3Dihub

Selenium – Health Professional Fact Sheet. (2021, March 26). NIH Office of Dietary Supplements. Retrieved July 6, 2023, from https://ods.od.nih.gov/factsheets/Selenium-HealthProfessional/#h2

Selenium | The Nutrition Source | Harvard T.H. Chan School of Public Health. (n.d.). Harvard T.H. Chan School of Public Health. Retrieved July 6, 2023, from https://www.hsph.harvard.edu/nutritionsource/selenium/

About the author

Anna Roell

Anna is a trained nurse and health economist specializing in epidemiology, combining her medical and scientific interests. Her goal is to improve others' understanding of medical information and to communicate it in an understandable way. Anna is originally from Germany and now lives in Amsterdam. What she appreciates most about Amsterdam is the open-minded, active attitude of the people, the markets, and the beautiful nature in the areas surrounding Amsterdam.