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BIEN-ETRE Everything you need to know about selenium


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Selenium is an antioxidant trace element with multiple virtues that plays a key role in human health. Discovered in 1817, it is essential for the proper functioning of the body and is involved in the activity of more than 200 enzymes. Since the body is not capable of synthesizing it, it is essential, even vital, to provide it through food or supplementation. From studies carried out in the 1950s, we know that selenium has recognized antioxidant properties which allow it to effectively fight against free radicals, these molecules, which in large quantities have a harmful impact on our cells. It is defined by ANSES as “an essential constituent of certain antioxidant enzymes. It thus participates in the fight against free radicals. It also has a stimulating effect on immunity and therefore generally contributes to the body's defense reactions.

Everyone should make sure to provide enough of it to their body in order to preserve their health, stimulate their immunity and protect their body from premature cellular aging. However, selenium intake must be controlled due to the risk of overdose.

We tell you more about it!

Properties of selenium

Stored in the liver and kidneys, it is truly essential for the proper functioning of the body, but not being manufactured by the body, it is absolutely necessary to provide it daily to the body. Protection of cells, support of the immune system, detoxification of the body, hormonal metabolism etc. Selenium has many benefits for the body. Researchers are currently conducting a study on the potential beneficial effects of this mineral in the prevention of colon and prostate cancer.

It has antioxidant properties

Antioxidants are compounds found in foods that prevent cell damage caused by free radicals. Our sedentary lifestyles, smoking, alcohol consumption and stress lead to an excess of free radicals, which are the cause of oxidative stress which gradually damages healthy cells in the body. Oxidative stress has thus been linked to chronic diseases such as heart disease, Alzheimer's disease and cancer, as well as premature aging and the risk of stroke.

Antioxidants like selenium help reduce oxidative stress in two ways: they work by neutralizing excess free radicals and by protecting cells from their damage. To maximize its protective effect, selenium is often combined with other antioxidant nutrients such as vitamins A, C and E.

Many factors lead to an overproduction of free radicals such as pollution, alcohol, tobacco, illness, stress, or the sun. These free radicals, the cause of oxidative stress, accumulate in the body and damage our cells. This excess accelerates the aging of cells, tissues and organs and thus reduces the functional capacities of the body. Selenium is able to counter this phenomenon thanks to its powerful antioxidant properties. Indeed, it is one of the molecules playing a major antioxidant role. By fighting against oxidative stress, it protects cells and promotes the slowing down of cellular aging. Selenium is in fact part of the composition of several enzymes responsible for neutralizing excess free radicals in the body. It activates the production of glutathione peroxidase, an enzyme which, in synergy with vitamin E, helps protect cells from oxidative stress and therefore preserve the integrity of their membranes. This is why we often find selenium in food supplements with antioxidant purposes, associated with vitamin E and sometimes C. Due to its antioxidant action, selenium also contributes to the radiance of the skin and robustness. nails and hair.

It helps to strengthen immunity

The immune system keeps the body healthy by identifying and fighting potential threats, particularly bacteria, viruses and parasites. Studies have shown that increased blood levels of selenium are associated with an increased immune response and that a deficiency increases the risk of infections.

Selenium is known as the gold standard for boosting immunity. Thanks to its immunostimulating function, it notably influences the functioning of components of the immune system (lymphocytes, cytokines, etc.) by increasing their production. Its antioxidant properties also allow it to protect the body's natural defenses and thus have a preventive action on certain diseases. Finally, it prevents repeated infections thanks to its anti-inflammatory properties. Selenium is therefore able to give a real boost to our immune system.

It improves blood circulation and may reduce the risk of heart disease

Selenium may help reduce the risk of heart disease by decreasing inflammation and oxidative stress in the body. Oxidative stress and inflammation have been linked to atherosclerosis, or the buildup of plaque in the arteries, which causes the majority of strokes, heart attacks, and heart disease.

It helps regulate thyroid function

Selenium is important for the proper functioning of the thyroid gland. Thyroid tissue is the largest store of selenium in the human body. It is located in the neck and produces the hormones T3 and T4. Indeed, selenium is involved in the regulation of the metabolism of thyroid hormones.

This powerful mineral helps protect the thyroid from oxidative damage and plays an essential role in the production of thyroid hormones. Maintaining a healthy thyroid gland is crucial since it is considered one of the conductors of our body: it stimulates metabolism, promotes bone strength, modulates cholesterol and blood sugar levels, regulates body temperature, controls heart rate and finally, regulates intestinal transit. When the thyroid functions poorly, different disorders appear.

It reduces asthma symptoms

Asthma is a chronic disease that affects the airways that carry air in and out of the lungs. These airways become inflamed and begin to narrow, causing symptoms such as wheezing, shortness of breath, chest tightness, and coughing.

Asthma has been associated with increased levels of oxidative stress and inflammation in the body. Due to selenium 's ability to reduce inflammation, some studies suggest that this mineral may help reduce asthma-related symptoms. Research suggests that people with asthma have lower blood levels of selenium .

It stimulates fertility

Selenium is necessary for the proper production and motility of sperm, two key elements involved in conception and which help limit the risks of infertility. Furthermore, the antioxidant power of selenium protects the fatty acids that make up spermatozoa against oxidation. Finally, some studies show that selenium may also reduce a woman's risk of miscarriage, although to date, more research has focused on its link to male infertility.

It strengthens skin, nails and hair

The antioxidant power of selenium is necessary to maintain skin, nails and hair in good condition. Therefore, when they are fragile, it may indicate insufficient absorption of selenium . Pale skin or intense white crescents of nails can be signs of chronic selenium deficiency, as can heavy, uniform hair loss. Good to know: its benefits on our tissues are maximized when combined with zinc.

The best sources of selenium

Selenium is present naturally in the soil and therefore we find it in our food through plants, in which they accumulate, or the animals which consume them. To meet its needs for selenium , the body draws it from food. There are many foods rich in selenium . This trace element is particularly present in products of animal origin, whether from the sea or not: fish and shellfish, meat, cold meats, eggs, offal and cheese. Selenium can also be provided by oilseeds (and particularly Brazil nuts), legumes and cereals.

Thus, a balanced diet must cover the body's selenium needs. However, the quantity of this trace element in foods strongly depends on its content in cultivated soils and can sometimes not be sufficient for the proper functioning of the body. This is why in certain cases it is recommended to supplement with selenium.

The amount of selenium in plant foods varies depending on the selenium content of the soil in which they were grown. Likewise, the selenium content of animal products depends on that of the plants with which they were fed. It is therefore important to adopt a varied diet that includes various sources of this important mineral.

Daily selenium intake

What are the daily needs?

Selenium requirements are of the order of a few tens of micrograms. On average, the recommended daily intake is 55 mcg/day for adults. It is important to note that the recommended nutritional intakes (ANC) differ depending on the age, sex, and physiological state of the person concerned. The ANC for the elderly are 60 to 80 µg of selenium , for men, pregnant and lactating women they are 60 µg, for women and adolescents over 12 years old they are 50 µg and finally for children under 12 years old they are 20 to 45 µg.

Selenium deficiencies

According to certain studies, the French have selenium deficiencies. Indeed, due to the poverty of the soil in France, plants and foods of animal origin are automatically poorer in selenium . Additionally, food refining, which removes the outer husk of cereal grains, also removes selenium since it is exclusively present in the grain husk. So, eating pasta, bread and white rice today means eating less selenium than in the past.

Selenium supplementation

We know that a selenium deficiency can cause muscle pain, hair loss, chronic fatigue, premature aging of the body, thyroid dysfunction, heart problems or even a decline in the immune system. In the most severe cases, it can even cause Keshan disease, a cardiomyopathy which causes heart failure and can lead to death.

This is why it is sometimes advisable to supplement with selenium . This type of food supplement is indicated to combat oxidative stress, maintain the cardiac system, strengthen the immune system and to preserve the beauty of hair, skin and nails. Elderly people or people with digestive diseases that slow the absorption of micronutrients should especially take care to get enough.

Although some studies report declining selenium intakes among the French, deficiencies in this micronutrient remain rare, especially for people who have no health concerns.

Risks of overdose

At very high doses, selenium can become toxic. When intake is consistently greater than 400 micrograms of selenium per day, certain health problems may occur. Chronic overconsumption can lead to toxic overexposure. This poisoning is called selenosis and results in intense fatigue, damaged nails, hair loss, dry skin, and digestive problems. The use of food supplements rich in selenium is not recommended for pregnant and breastfeeding women, children and people with goiter.

If you have the slightest doubt or if you need additional information, seek the advice of your doctor or another health professional (pharmacist, dietitian, etc.) to avoid any excess selenium that is harmful to your health.


Solène Senejko

Ingénieure Alimentation & Santé