Sélénium complément alimentaire

Selenium is an essential trace element that is often overlooked, yet it plays a fundamental role in the proper functioning of our bodies. This element, naturally found in foods like Brazil nuts, seafood, and certain meats, is also available as a dietary supplement.

We will discuss the benefits of selenium, its impact on the human body, and provide practical advice for choosing a quality supplement.

What is Selenium?

Selenium is a trace element discovered in 1817 by Swedish chemist Jöns Jacob Berzelius. Unlike some nutrients that the body can create, selenium cannot be synthesized by the body. Therefore, it must be obtained through diet or, if necessary, in supplement form. Once ingested, selenium is absorbed in the intestine and distributed to various organs in the body, including muscles, liver, kidneys, and the thyroid gland. In these organs, it is incorporated into selenoproteins, proteins that perform important functions in the human body.

Due to its small quantity in the body, it is essential to have an adequate dietary intake to maintain balance, as selenium plays a crucial role in several biological functions.

Benefits of Selenium

Selenium is an element with multiple health benefits, supporting several essential functions in the human body. Here are the main benefits of selenium:

• Contributes to normal thyroid function: A study by Wang et al. (2023) showed that selenium plays a role in the function of the thyroid axis (1).
• Contributes to protecting cells from oxidative stress: Selenium is a powerful antioxidant.
• Contributes to the normal functioning of the immune system.
• Contributes to the maintenance of normal nails and hair.

Where is selenium found in the body?

Selenium is primarily stored in:

• Muscles: house about 50% of the body's total selenium.
• Liver: another important reservoir of selenium.
• Kidneys: which participate in its metabolism and excretion.
• Thyroid gland: where it plays an essential role in normal thyroid function.

Foods rich in selenium

Selenium is found in many foods, both animal and plant-based. Here are some examples of foods particularly rich in this nutrient:

• Brazil nuts (richest in selenium)
• Fish and seafood: tuna, sardines, shrimp, cod
• Meats: chicken, turkey, beef liver
• Whole grains: brown rice, oats
• Vegetables: mushrooms, spinach, broccoli
• Sunflower seeds and cashews

However, the concentration of selenium in foods can vary depending on the soil content where crops are grown. In some regions, particularly areas with selenium-poor soil, foods may contain less of this trace element. This is why, in some cases, a dietary supplement may be recommended to increase the intake of this nutrient.

Why take a selenium supplement?

Although selenium is naturally present in many foods, it can sometimes be difficult to get enough from diet alone, especially in certain specific situations. In these cases, selenium supplementation can be beneficial to increase intake.

1. Athletes

Athletes, especially those who engage in intense activities, may have selenium needs due to mineral loss in sweat and to support antioxidant functions (prevention of cellular damage induced by intense physical exercise).

2. Vegetarians and Vegans

The main dietary sources of selenium, such as meat and fish, are excluded from vegetarian and vegan diets. Although some plant foods, such as Brazil nuts and certain seeds, contain selenium, their concentration can vary depending on the quality of the soil in which they were grown.

3. People living in selenium-poor regions

In some regions of the world where the soil is naturally poor in selenium, locally grown foods may not contain enough.

A dietary supplement can help increase intake, but it is essential to choose a quality product and follow recommended doses.

How to choose a selenium supplement?

Choosing a selenium supplement should not be done at random. To ensure its effectiveness and safety, several essential criteria must be taken into account:

1. The form of selenium

Not all forms of selenium are equal in terms of absorption and bioavailability. Prioritize organic forms, especially L-selenomethionine, which is better assimilated by the body than inorganic forms like selenite or sodium selenite. L-selenomethionine is a natural form of selenium, in which the trace element is bound to an amino acid.

2. The appropriate dosage

For daily use, a dosage between 55 µg and 100 µg of selenium from L-selenomethionine is generally recommended for adults. This dosage allows for covering physiological needs without risk of overdose. It is important to note that selenium is effective at low doses, and an excess can lead to adverse effects. The EFSA sets a safety threshold of 255 µg/day for adults.

3. Product quality

Opt for supplements from reliable brands, known for their transparency and commitment to quality. Verify that the product clearly displays the form of selenium, the dosage per serving, and the complete list of ingredients.

Precautions for use

Selenium is an essential trace element, but excessive intake can lead to adverse effects. Unlike some nutrients whose excess is easily eliminated by the body, selenium accumulates in tissues, particularly the liver, kidneys, and muscles.

According to the European Food Safety Authority (EFSA), the maximum safe threshold is set at 255 µg per day for a healthy adult. Exceeding this limit, especially over a long period, can lead to symptoms of toxicity.

To avoid any risk, it is essential to follow the recommended doses from health authorities and manufacturers, taking into account dietary intake already present in your daily diet. Furthermore, taking supplements should never replace a balanced diet.

Finally, before starting any supplementation, especially in cases of thyroid disorders or while taking medical treatments, it is highly advisable to consult a healthcare professional (doctor, dietitian) to determine if supplementation is necessary and under what conditions it can be beneficial.

In summary: what to remember about selenium supplements

Selenium is an important trace element for many bodily functions. Adequate intake is essential to maintain its functions in the body.

However, it is crucial to choose quality products and follow recommended doses. If in doubt, always consult a healthcare professional for personalized advice.

Sources:

1. Wang F, Li C, Li S, Cui L, Zhao J, Liao L. Selenium and thyroid diseases. Front Endocrinol. DOI: https://doi.org/10.3389/fendo.2023.1133000
2. European Food Safety Authority (EFSA). Scientific opinion on the tolerable upper intake level for selenium. EFSA Journal. 2023
3. Agence nationale de sécurité sanitaire de l’alimentation, de l’environnement et du travail (Anses). Les minéraux. 2025