Selenium is a trace element that the body needs only in small amounts, yet its importance for health is disproportionately large. It is essential for the proper functioning of the thyroid and the immune system, and it helps protect cells against oxidative stress. Both an excess of selenium and a selenium deficiency can affect the body unfavourably, so it is worth knowing when an increased intake of this nutrient may be justified and how to look after an adequate supply of it safely.
Contents
- Why is selenium so important for the body?
- What functions does selenium perform in the body?
- Selenium deficiency – who is most at risk?
- Symptoms of selenium deficiency
- Selenium and thyroid health
- Does supplementation help in thyroid disorders?
- The influence of selenium on immunity
- How can you supply an adequate amount of selenium?
- When is it worth considering supplementation?
- Can an excess of selenium also do harm?
- Summary
- Frequently asked questions (FAQ)
- How does a selenium deficiency show itself?
- What flushes selenium out?
- How can selenium be replenished quickly?
- References
Why is selenium so important for the body?
Although selenium belongs to the micronutrients, it performs many significant biological functions. It is a component of more than 20 selenoproteins, that is, proteins involved in, among other things, protecting cells against oxidative damage, regulating inflammatory processes and the metabolism of thyroid hormones [1,2].
The human body cannot synthesise selenium on its own. It has to be supplied through the diet. Its content in foods depends primarily on the amount of selenium present in the soil, which is why the intake of this element may differ between individual regions of the world.
What functions does selenium perform in the body?
The most important roles of selenium include:
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a part in the normal functioning of the thyroid;
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supporting the natural mechanisms of immunity;
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protecting cells against oxidative stress;
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a part in reproductive processes in men;
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supporting the normal work of antioxidant enzymes [2,4].
It is worth stressing that selenium does not act on its own. Many of its functions depend on cooperation with other nutrients, including iodine, zinc, iron and vitamin E.
Selenium deficiency – who is most at risk?
A selenium deficiency may go on for a long time without any characteristic symptoms. The risk of it developing depends not only on the way you eat, but also on chronic illnesses, age and place of residence.
The groups at increased risk include people following very restrictive elimination diets, patients with malabsorption disorders, people fed parenterally and patients with chronic conditions of the digestive tract [1,5]. It is precisely in these population groups that maintaining a normal selenium level may be somewhat more difficult.
Symptoms of selenium deficiency
The symptoms of a deficiency are non-specific and may have many other causes. Those described most often include:
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chronic fatigue;
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muscle weakness;
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weakened immunity;
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mental disturbances;
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slower recovery of the body;
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hair loss and brittle nails [2,5].
A selenium deficiency cannot be diagnosed on the basis of symptoms alone. If it is suspected, the decision about testing should be taken by a doctor.
Selenium and thyroid health
The thyroid is one of the organs with the highest selenium concentration in the body. This is no accident. Selenoproteins take part in the conversion of thyroxine (T4) into the active triiodothyronine (T3), the hormone responsible for many metabolic processes.
Does supplementation help in thyroid disorders?
Most of the research concerns autoimmune thyroiditis (Hashimoto’s disease). Some meta-analyses suggest that selenium supplementation may lead to a reduction in the concentration of anti-thyroid antibodies in selected patients. This does not mean, however, that it is a standard treatment or that it replaces the therapy recommended by an endocrinologist [7,8].
Current guidelines stress that the decision about supplementation should be individual and should take into account nutritional status, diet and test results. Routine use of selenium is not recommended for everyone with thyroid disorders.
The influence of selenium on immunity
The immune system requires an adequate supply of many vitamins and minerals. Selenium takes part in regulating the immune response and helps limit the excessive oxidative stress (which lowers the level of free radicals) that accompanies inflammatory processes.
Studies indicate that both a deficiency and an excess of selenium may disturb the normal functioning of immunity. For this reason the aim is not to take the highest possible doses, but to maintain an optimal level of this element [2,9].
It is worth remembering that supplementation does not replace a healthy diet, an adequate amount of sleep, physical activity or protective vaccinations.
How can you supply an adequate amount of selenium?
A varied diet remains the best source of selenium. The foods containing this element are above all sea fish, seafood, meat, eggs, wholegrain products and Brazil nuts. It has to be remembered, however, that the selenium content of Brazil nuts can differ considerably depending on where they were grown.
When is it worth considering supplementation?
Supplementation may be considered in people at increased risk of a deficiency, or when a doctor establishes an insufficient supply of this nutrient. In such a case it is worth choosing products of known quality and with a transparent composition, for example BestSelenium.
The full product range can be found in the category Food supplements – BEST LAB, while products supporting immunity are available in the section Supplements for immunity and strengthening – BEST LAB.
Before starting long-term supplementation it is worth consulting a doctor or pharmacist, especially in the case of chronic illnesses and when taking medication.
Can an excess of selenium also do harm?
Just like a deficiency, an excessive supply of selenium is not beneficial either. Exceeding the tolerable upper intake level over a long period may lead to the development of selenosis.
The symptoms of an excess include, among others, brittle nails, hair loss, a metallic aftertaste in the mouth, complaints from the digestive tract and a characteristic garlicky smell of the breath [2,3].
Summary
Selenium is an essential micronutrient involved in the normal work of the thyroid, the immune system and the mechanisms that protect cells against oxidative stress. A deficiency may increase the risk of health disorders, but the symptoms are usually not very characteristic and require appropriate testing.
Current scientific knowledge does not confirm that routine selenium supplementation is justified in everyone. A balanced diet remains the best solution, and the decision to use products containing selenium is worth taking individually, taking into account state of health, the way you eat and a specialist’s recommendations.
Frequently asked questions (FAQ)
How does a selenium deficiency show itself?
A deficiency may show itself through, among other things, chronic fatigue, muscle weakness, more frequent infections, excessive hair loss and brittle nails, and slower recovery of the body. The symptoms are not characteristic, however, and may also result from many other conditions.
What flushes selenium out?
Most often the cause of a deficiency is not the flushing out of this element but a low selenium content in the diet. Some chronic illnesses that reduce the absorption of selenium may also be significant.
How can selenium be replenished quickly?
The foundation is a diet rich in natural sources of selenium. If a doctor or dietitian considers it justified, supplementation with an appropriately chosen product may be considered. The causes of an excess of selenium, which is above all excessive supplementation, may lead to complaints from the digestive system and other serious health problems.