Selenium Danger: Should You Be Wary?

What is selenium?

Selenium is an essential trace element, meaning it's a nutrient the body needs in very small amounts, but whose absence can lead to imbalances. It plays a fundamental role in several vital functions:

• It contributes to the normal functioning of the immune system,
• It protects cells against oxidative stress, thanks to its antioxidant action,
• It participates in thyroid function.

Our body does not produce selenium: it must therefore be supplied through food or food supplements.

Where is selenium found in the body?

Once absorbed by the intestine, selenium is distributed throughout the body. It is present in almost all tissues, but certain organs concentrate more of it, due to their high need for selenium.

• The thyroid gland: this is one of the organs richest in selenium per gram of tissue.
• The liver: a key metabolic organ, it stores and recycles selenium.
• The kidneys: they are involved in the elimination and regulation of circulating selenium levels.
• The pancreas, spleen, and testes: these organs also contain notable amounts of selenium, linked to their enzymatic and hormonal activity.
• Muscles and blood: although in lower concentrations, these tissues represent a significant portion of the total body selenium, due to their volume.

Where to find selenium in food?

Selenium is present in many foods, especially those of animal origin and some plants. Here are some examples of food sources of selenium:

• Brazil nuts: very rich, they contain an average of 70 to 90 µg per nut.
• Fish and seafood: tuna, sardines, mackerel, shrimp, oysters... They are good sources of selenium, in addition to providing omega-3s.
• Eggs, offal (liver, kidneys): contain significant amounts.
• Whole grains, legumes (lentils, chickpeas): the selenium content depends on the richness of the soil where these plants grew.

Selenium danger: is consumption regulated?

Selenium plays an essential role in the functioning of the body, but like any micronutrient, it must be consumed in appropriate amounts. Regular excess can pose health risks. It is therefore essential to adopt a reasoned approach.

1. What ANSES recommends

The French Agency for Food, Environmental and Occupational Health & Safety (ANSES) defines adequate intakes to cover the physiological needs of adults:

• 70 µg/day for adult men.
• 70 µg/day for adult women.

ANSES (2) also sets an upper safety limit of 250 µg/day for adults. Exceeding this limit regularly can lead to effects such as:
- Digestive disorders,
- In some cases, breath with a characteristic garlic odor.

2. Tips for responsible consumption

To avoid any risk related to excessive selenium intake, it is recommended to adopt some simple good practices:

• Prioritize natural food sources: a balanced diet, rich in fish, seafood, eggs, legumes, or Brazil nuts, is generally sufficient to cover needs.
• Avoid self-medication: taking food supplements without medical supervision can lead to unintentional overdose.
• Read labels carefully: some supplements combine several sources of selenium (selenite, selenomethionine), which can easily lead to exceeding the maximum intake without realizing it.

How to choose your selenium supplement safely?

While diet is generally sufficient to cover selenium needs, certain specific situations may justify supplementation. But be careful: not all supplements are equal, and improper use can lead to undesirable effects.

Here are the essential criteria to consider when choosing a quality selenium supplement.

1. Respect recommended doses

First and foremost, it is imperative not to exceed the recommended daily intakes:

• Adequate intake (ANSES): 70 µg/day for men and women.
• Maximum tolerable threshold: 250 µg/day (all sources combined).

Good to know: Some supplements combine several forms of selenium or are associated with other antioxidants (zinc, vitamin E). Carefully check the cumulative dosages on the label.

2. Choose the right form of selenium

There are several forms of selenium in food supplements:

• Selenomethionine (organic form, often extracted from enriched yeast): better bioavailability, better absorbed by the body.
• Sodium selenite or sodium selenate (inorganic forms): less well assimilated, but used in some products.

For optimal effectiveness and safe absorption, prefer supplements based on selenomethionine, which are often better tolerated.

3. Check the manufacturer's quality

Opt for a laboratory that is:

• Reputable and transparent, with clear ingredient traceability,
• Respecting European or French manufacturing standards (e.g., ISO 22000, HACCP),
• Providing conformity analyses or analysis certificates upon request.

4. Adapt supplementation to your actual needs

Supplementation should never be automatic. It is recommended to:

- Consult a healthcare professional (doctor, dietitian) before starting a supplement.

Selenium danger: in summary

Selenium is an essential trace element, involved in the functioning of the immune system, hormonal regulation, and the protection of cells against oxidative stress. It is found in many foods, such as fish, eggs, legumes, and Brazil nuts.

However, like any micronutrient, selenium must be consumed in appropriate amounts. Excess, particularly linked to unsupervised supplementation, can lead to undesirable effects. If supplementation is needed, it is essential to choose a quality product, well-dosed, and adapted to your actual needs, always in consultation with a healthcare professional.