Selenium: Important for more than just the thyroid article image

Selenium: Important for more than just the thyroid

Selenium is a mineral, or rather a so-called trace element and element, which is needed for a number of important functions in the body. Among other things, selenium is needed for the function of the thyroid gland, the function of the immune system, sperm production and plays an important role for hair and nails.

Selenium is also an antioxidant that protects the body's cells against oxidative stress. Selenium is found in food but can also be taken via dietary supplements.

Selenium and the thyroid gland

What selenium is perhaps best known for, and which above all many women talk about, is its effect on the functions of the thyroid gland.

Why women in particular may be a little extra interested in selenium is because problems with the thyroid gland mainly affect women. It can be about both under- and over-functioning. For the thyroid gland to function optimally, it needs certain nutrients. Some examples are the minerals selenium and iodine, but also certain amino acids are important. Further down, we describe how selenium affects the thyroid gland.

Selenium is needed for the thyroid gland to function optimally

The thyroid gland is a gland that produces thyroid hormones, such as thyroxine (T4) and triiodothyronine (T3), which play a central role in regulating the body's metabolism and energy levels.

Selenium is an essential component of selenoproteins, and one of these important proteins is thyroxine deiodinase (DIO). DIO is an enzyme that aids in the conversion of the inactive form of the thyroid hormone T4 into the active form T3. T3 is the form of thyroid hormone that has a direct effect on the body's cells and regulates metabolism.

Selenium has antioxidant properties and helps protect thyroid cells from damage caused by free radicals and oxidative stress. A balanced level of selenium can support the normal functioning of the thyroid gland.

Selenium and other health benefits

Immune system

Selenium is an important mineral that plays a role in the body's immune system. Here are some ways selenium affects the immune system:

  1. Antioxidant function: Selenium acts as an important component of several antioxidant enzymes, especially the selenoproteins. These enzymes help fight free radicals in the body, reducing oxidative stress. Oxidative stress can damage cells and negatively affect the function of the immune system.
  2. Immune response: Selenium is involved in the regulation of the immune system's response to infections and inflammation. Selenoproteins help modulate cytokines, which are proteins that act as signals for the immune system and regulate inflammation and immune cell activity.
  3. Virus defense: Selenium plays a role in the defense against viral infections. Research has shown that a lack of selenium can increase susceptibility to viral infections.
  4. Cell mediation: Selenium is necessary to maintain the proper function of T cells, a type of white blood cell that is central to the body's defense against infection. Low levels of selenium can affect the ability of T cells to fight viruses and bacteria.


Selenium is needed for the production of healthy sperm. It is an important component of the selenoprotein called selenoprotein P, and it has been shown to play a role in sperm production and sperm quality. Low levels of selenium can affect sperm quality and motility.

Selenium is also important for female fertility. It is involved in ovulation and early stages of embryo development.

Hair and nails

Selenium plays an important role in hair and nails in several ways.

  1. Antioxidant effects: Selenium acts as part of so-called selenoproteins, including glutathione peroxidase, which have antioxidant properties. Antioxidants help protect cells from oxidative stress and free radicals. Since hair and nails are exposed to environmental factors and free radicals, selenium can help reduce damage to these structures and support their health.
  2. Hair growth and hair quality: Selenium is involved in the formation of hair proteins and is necessary for hair to grow and feel good. Selenium supports the production of selenoproteins, which are important for hair structure and growth.
  3. Nail growth and nail health: Nails mainly consist of keratin, a protein that selenium also affects. Selenium is needed for the production of keratin and other proteins that are important for nails.

How much selenium per day do we need?

The recommended daily allowance (RDI) micrograms of selenium per day:

Infants 7-11 months: 20 micrograms

Children 1-3 years: 20 micrograms

Children 4-6 years: 25 micrograms

Children 7-10 years: 40 micrograms

Girls 11-14 years: 60 micrograms

Boys 11-14 years: 65 micrograms

Girls 15-17 years: 70 micrograms

Boys 15-17 years: 85 micrograms

Women: 75 micrograms

Men: 90 micrograms

Pregnant women: 90 micrograms

Breastfeeding: 85 micrograms

Selenium deficiency is common in Sweden, because the soils are selenium poor in several areas

It is known that some parts of Sweden have selenium-poor soil, and this can affect the selenium content of crops grown in these areas. Therefore, people living in these regions or who obtain a large part of their diet from local crops may have difficulty meeting their selenium needs through diet alone.

If there is concern about a deficiency and the selenium intake through the diet is considered insufficient, supplementation of selenium can be a supplement.

How can you increase your intake of selenium?

Selenium is found naturally in a range of foods, and the intake of this mineral can vary depending on diet and geographical factors. Here are some foods that are known to be good sources of selenium:

  1. Nuts and seeds: Brazil nuts are particularly rich in selenium. Just a few Brazil nuts per day can meet the daily need for selenium. Other nuts and seeds such as sunflower seeds and sesame seeds also contain selenium but in smaller amounts.
  2. Fish and shellfish: Fish and shellfish are excellent sources of selenium. Tuna, sardines, salmon and crab are examples of fish and shellfish that contain significant amounts of selenium.
  3. Meat: Meat, especially lean meats like chicken and turkey, are a good source of selenium. Beef and pork also contain selenium, but the amount can vary.
  4. Dairy products: Milk and cheese, especially cheeses like cheddar and gouda, contain selenium. Eggs are also a source of selenium, especially if the hens are fed feed that is rich in minerals.
  5. Whole grain products: Some whole grain products, such as whole grain bread and whole grain pasta, contain selenium. However, it is important to note that the selenium content of whole grain products can vary depending on the selenium content of the soil in the region where the crops are grown.
  6. Vegetables: Some vegetables contain selenium, although levels may be lower compared to meat and fish. Broccoli, spinach and garlic are examples of vegetables that contribute to selenium intake.

A varied diet with the above foods can provide the body with its daily needs, but studies show that adults ingest an average of 40-50 micrograms of selenium per day. The recommended daily intake of selenium is between 75-90 micrograms per day for adults.

A dietary supplement with selenium can act as a supplement to the daily diet to ensure optimal levels.

Common questions and answers about Selenium

Selenium is a bit of a mystery that not everyone knows that well. We want to change that, as selenium is very important for the body to feel good. Below you will find common questions and answers about selenium.

What is selenium good for?

  • Selenium helps to protect the cells against oxidative stress.
  • Selenium contributes to the normal functioning of the immune system.
  • Selenium contributes to normal spermatogenesis.
  • Selenium contributes to normal thyroid function.
  • Selenium contributes to maintaining normal hair.
  • Selenium contributes to maintaining normal nails.

In which food is there a lot of selenium?

Selenium is not found in large quantities in food, but certain foods, in combination with each other, can still give us significant amounts of selenium. The Brazil nut is the food that contains the highest levels, but it depends on where it was harvested as the soil has very variable selenium levels.

  • Brazil nuts and other nuts and seeds
  • Fish and seafood
  • Chicken and turkey
  • Cheddar and Gouda cheese
  • Wholemeal bread and wholemeal pasta
  • Broccoli, spinach and garlic

How do you know if you are deficient in selenium?

Selenium is an important mineral for the normal functioning of the body, and a lack of selenium can lead to various symptoms and health problems. Here are some possible symptoms and signs of selenium deficiency:

  1. Impaired immune system: Selenium is linked to the function of the immune system, and a lack of selenium can result in a reduced immune response. It can increase the body's susceptibility to infections and other diseases.
  2. Fatigue and weakness: Selenium is involved in energy production in the body, and a lack of this mineral can lead to increased fatigue and weakness.
  3. Impaired thyroid function: Because selenium is an important component of selenoproteins, including the deiodinase enzyme, selenium deficiency can affect thyroid function.
  4. Hair loss and brittle nails Selenium is involved in the formation of hair and nail proteins. Lack of selenium can result in hair loss and deterioration of nail health.
  5. Skin problems: Selenium is also important for skin health. Selenium deficiency can be linked to skin problems such as dryness and redness.
  6. Impaired fertility: Selenium is involved in the reproductive system, and selenium deficiency can affect fertility in both men and women.

Who needs selenium?

Everyone needs selenium as it is an essential mineral and the body cannot produce it on its own. There are groups that may have an increased need for selenium for various reasons:

  1. People in areas with selenium-deficient soils: Selenium levels in soil vary around the world. People who live in areas where the soil is low in selenium may have a harder time getting enough selenium through their diet. Sweden generally has selenium-poor soils compared to some other areas in the world. However, the selenium content of the soil varies across the country, and there are regions where the selenium content is higher than in others.
  2. People with certain gastrointestinal problems: Certain gastrointestinal problems, such as Crohn's disease, celiac disease or other conditions that affect nutrient absorption, can lead to a reduced ability to absorb selenium from the diet.
  3. People undergoing dialysis: People undergoing dialysis for kidney disease may lose selenium in the urine and may therefore have an increased need for selenium.
  4. Pregnant and lactating women: Pregnant and lactating women may have an increased need for selenium to support fetal growth and development.
  5. People with certain diseases: Certain medical conditions, such as inflammatory diseases, thyroid disease and kidney disease can increase the body's need for selenium.

If you take medication or suffer from an illness, you should always consult a doctor before taking selenium supplements.

Can you take selenium and zinc at the same time?

Yes, zinc and selenium work well together and have synergistic effects. Both are trace minerals that are important for various aspects of body function. Here are some ways zinc and selenium work together:

  1. The immune system: Both zinc and selenium play a role in the functioning of the immune system. They are involved in the production of white blood cells and other components of the immune system. A combination of zinc and selenium can support the normal functions of the immune system.
  2. Antioxidant Defense: Both zinc and selenium have antioxidant properties and can help protect cells from damage caused by free radicals. These free radicals are formed naturally in the body and can lead to cell damage and aging.
  3. Reproduction and fertility: Both zinc and selenium are important for the reproductive system in both men and women. They can affect sperm production in men and egg maturation in women.

Which vegetables contain selenium?

Selenium is found in varying amounts in different foods, but most vegetables generally contain low levels of selenium compared to other food groups. Animal products, nuts, seeds and grains tend to be richer sources of selenium. Despite this, there are some vegetables that contain selenium, although the amounts may be limited. Here are some examples of vegetables that contain selenium:

  1. Breads and cereals: Some breads and cereals can contain selenium, especially if they are made with selenium-rich flour.
  2. Mushrooms: Mushrooms, especially chanterelles, have relatively high levels of selenium compared to other vegetables.
  3. Lentils: Lentils may contain small amounts of selenium.
  4. Cooked asparagus: Asparagus can be a source of selenium, especially if grown in areas with selenium-rich soil.
  5. Spinach and broccoli: Spinach and broccoli contain selenium, but the amounts are usually not very high.

What time of day is it best to take the sling?

It does not matter what time of day you take your selenium supplement. We recommend taking selenium with any meal.