Selenium – A Trace Element Your Thyroid, Immune and Cellular Function Need

Selenium is rarely talked about, even though its role in ensuring the health of the body is great. Selenium is a trace element belonging to the group of minerals. The very definition of a trace element — a chemical element found in organisms in extremely small quantities and necessary for vital functions — betrays how important this substance is. Selenium plays an important role in the metabolism of thyroid hormones, DNA synthesis, reproductive function, and in protecting the body from oxidative stress and infections.

Let's get to know this powerful microelement better — what it is, its benefits, deficiency symptoms, and everything else important about selenium.

What is Selenium?

The body needs selenium in small amounts, but the impact of this trace element on health is great. The body does not synthesize selenium itself, and therefore we must get enough of it from food or supplements. The body stores selenium mainly in the liver, kidneys, thyroid gland, blood and reproductive tissues, but this is for functional use, not for long-term storage.

Selenium is an essential trace element, the effects of which are mainly exerted through selenoproteins. The full functions of these selenium-containing proteins are not yet fully understood, but it is known that they play a very important role in human health. Selenoproteins are central to the functioning of cells and their normal functioning depends on an adequate supply of selenium.

One of the main roles of selenium is to regulate thyroid hormone production, but it also has other important functions. Let's get to know better.

Benefits of Selenium for the Body

Selenium has a wide range of health benefits, including:

• Strong Antioxidant effect. Selenium supports the body's antioxidant defenses through selenoproteins, helping to neutralize harmful oxygen compounds and protect cells from oxidative stress.
• Strengthening the immune system. Selenium supports the immune system mainly through selenoproteins, supporting the normal function and survival of immune cells and helping to protect them from oxidative stress. They also regulate inflammation and the immune response. Selenium deficiency does weaken the immune response, but supplementing with selenium does not provide significant additional benefits if selenium levels in the body are already sufficient.
• Thyroid hormone regulation. Selenium supports normal thyroid function by helping the body produce and activate thyroid hormones and protecting the thyroid gland from oxidative stress.

• Cardiovascular protection. Selenium participates in the body's antioxidant and anti-inflammatory defenses and supports normal cellular function and metabolism, which is also important for heart and vascular health.
• Role supporting fertility (especially in men). Selenium supports normal spermatogenesis and helps protect germ cells from oxidative stress.
• Regulating the inflammatory response. Adequate selenium levels are associated with lower inflammatory markers and a more balanced immune response.

How Much Selenium does the Body Need?

The European Food Safety Authority (EFSA) has established an Adequate Intake (AI) for selenium. The AI is the amount that ensures that the level of selenoprotein P in the blood reaches a plateau, which EFSA considers a marker of adequate selenium supply.

Selenium Deficiency and its Symptoms

EFSA estimates that most Europeans have adequate selenium levels when they eat a varied diet. However, lower selenium levels may occur in areas where the soil is low in selenium and dietary selenium intake is low. This includes the Baltic countries, where the soil is naturally low in selenium.

Selenium deficiency in the body and genetic changes in the selenoprotein system are associated with many diseases, including heart and muscle diseases, immune disorders, neurological and hormonal disorders.

The distribution of selenium in the body is dynamic - in case of selenium deficiency, the body preferentially directs selenium to the thyroid gland and brain to maintain vital functions.

Symptoms of Selenium Deficiency

Selenium deficiency is known to be associated with problems in several body systems, including the cardiovascular, immune, and endocrine systems. Selenium deficiency can cause diseases such as Keshan disease and muscle and heart damage.

Possible signs of selenium deficiency include:

• Hair loss, brittle hair and nail
• Fatigue
• Brain fog, difficulty concentrating, or memory problems
• Muscle weakness and pain
• Weakened immune system
• Decreased fertility in men
• Thyroid disorders

These symptoms are non-specific, and a blood test is the best way to determine the body's selenium levels and possible deficiency.

ICONFIT's high-quality and highly bioavailable selenium supplement helps meet the body's daily selenium needs.

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Natural Sources of Selenium – Selenium from Food

The amount of selenium in plant foods depends on the amount of selenium in the soil where the food is grown. Rainfall, evaporation, pesticides, and pH levels can all affect soil selenium levels. The selenium levels in plant foods in turn affect the selenium levels in animals that eat those plants. However, animal protein is generally a good source of selenium.

Sources of selenium in food:

• Brazil nuts: very high in selenium
• Seafood: tuna, sardines, shrimp, cod, salmon, oysters, mussels
• Meat: pork, chicken, turkey, organ meats (liver)
• Grains and legumes: whole grain bread, brown rice, oatmeal, baked beans, lentils, sunflower seeds
• Dairy and eggs: cottage cheese, milk, eggs
• Vegetables: mushrooms, spinach, garlic, mango, turnip (content varies depending on soil)

How much selenium do selenium-rich foods contain? Brazil nuts are arguably the richest in selenium. Just a few nuts can cover your daily selenium needs.

Selenium Bioavailability

The bioavailability of selenium depends primarily on its chemical form, not so much on whether it comes from food or a supplement, but in general, selenium is well absorbed. A distinction is made between organic and inorganic selenium. Organic selenium, especially selenomethionine, is absorbed very well in the body (over 90%) and can be deposited in the body's proteins, acting as a selenium reserve. The bioavailability of inorganic selenite is usually lower, generally in the range of 70–80%. However, higher absorption does not automatically mean greater benefits - once the body's needs are covered, the functional effect of selenium does not increase further. Therefore, when it comes to selenium, "more" is not necessarily better. Especially in the case of supplements, long-term excessive consumption of which should be avoided.

The following factors and health conditions can make it difficult for the body to absorb selenium:

• Dialysis
• HIV
• Hypothyroidism – a condition in which the thyroid gland does not produce enough hormones

Selenium – When and How to Take it as a Supplement?

Although selenium is highly bioavailable, it is not selg-evident to obtain the amount of selenium the body needs from food. Especially in regions where the soil is low in selenium, which is why the daily diet may remain modest in terms of selenium content.

Selenium supplementation may be justified, especially if the amount obtained from food is insufficient, the diet is one-sided (including vegetarians and vegans) or the body's need for selenium has increased.

There is no scientifically proven best time to take selenium. Consistency is more important than a specific time. However, it is recommended to take selenium supplements with food, especially one that contains some fat. Taking selenium with food can also help prevent mild gastrointestinal discomfort in sensitive individuals, making it a good habit to get into on a daily and consistent basis.

Selenium Overabundance and Safety

When selenium intake is too high, the body does not store it, but increases excretion through urine, feces, and breath. Although the body does excrete excess selenium, this process is not efficient enough to prevent toxic selenium accumulation in the event of excessive intake, leading to selenosis, or selenium poisoning.

The range between the required and toxic amounts of selenium is very narrow, so it is important to stay within the recommended dosage. If you are taking any medications (especially thyroid medications), are pregnant, or are breastfeeding, consult a doctor before use.

Selenium deficiency can cause diseases (e.g. Keshan disease, muscle and heart damage), but excessive intake can lead to selenosis.

Symptoms of selenosis:

• Hair and nail damage
• Garlic-smelling breath
• Gastrointestinal disorders
• Neurological symptoms

EFSA set a new UL for selenium in 2023, or the maximum safe daily intake of selenium from all sources. The ULs are derived from average body weight.

Selenium UL:

• 1–3 years: 60 µg/day
• 4–6 years: 90 µg/day
• 7–10 years: 130 µg/day
• 11–14 years: 200 µg/day
• 15–17 years: 255 µg/day
• Adults (including pregnant and lactating women): 255 µg/day

Selenium and Zinc – a Collaboration that Works

Selenium, when consumed together with zinc, is a powerful tool in supporting health. They work synergistically, complementing each other and increasing effectiveness, especially in antioxidant protection.

The main benefits of combining selenium and zinc:

• Immune support: Both minerals are important for normal immune function and help the body fight infections.
• Antioxidant protection: protects cells from damage caused by oxidative stress.
• Thyroid function: Selenium is crucial for the synthesis and activation of thyroid hormones, which zinc also indirectly supports.
• Fertility support (especially in men): Zinc and selenium support normal spermatogenesis.
• Maintaining healthy hair, nails and skin.

  Meet ICONFIT Zinc & Selenium here

Selenium is a very necessary trace element for the body, which supports immunity, has a strong antioxidant effect and is the main regulator of thyroid hormone function. 
The bioavailability of selenium from food is very good, but the selenium content in food is in turn strongly influenced by the selenium content in the soil where the food is grown. Therefore, selenium deficiency is a common phenomenon in areas with selenium-poor soil. The need for selenium is U-shaped. Explained in detail, this means that both underconsumption and overconsumption can cause various health problems. Moderation is the key word here.

But if you are suffering from selenium deficiency, then high-quality and highly bioavailable selenium supplements from the ICONFIT will come to your aid. Check out the products  SIIN.

Links to sources:

1. Selenium, National Institutes of Health
2. Effects and Impact of Selenium on Human Health, A Review, MDPI
3. Regulation and function of selenoproteins in human disease, National Library of Medicine, PubMed
4. Scientific opinion on the tolerable upper intake level for selenium, EFSA Journal, European Food Safety Authority
5. ThyroidUK, Selenium Deficiency
6. 20 Foods Rich in Selenium, Healthline
7. Top 10 Foods Highest in Selenium, MyFoodData
8. Determination of Selenium Content in Food, Tartu Health Care College