Selenium deficiency: the most effective dietary supplements

Selenium is an essential trace element that plays a key role in protection against oxidative stress. It is particularly important for the integrity of cell membranes, thanks to its action on the enzyme glutathione peroxidase (GSH-Px). This enzyme is responsible for reducing oxidative damage by protecting lipids, lipoproteins, and DNA from damage caused by free radicals. In addition to its antioxidant properties, selenium participates in the body's detoxification by binding to certain heavy metals and xenobiotics, thereby forming metal-selenium complexes that are easier to eliminate. Selenium also plays a role in the regulation of thyroid hormones and supports the immune system. It exists in the body mainly in two forms: selenomethionine, found in plants, and selenocysteine, derived mainly from animal proteins. The most active and directly catalytic forms are the inorganic forms, such as sodium selenite.

Dietary sources of selenium

Foods rich in selenium are mainly of animal origin, with high concentrations in fish, shellfish, meat, and offal. Brazil nuts are particularly rich in selenium, as are certain plants such as garlic and broccoli, although their content depends heavily on the amount of selenium present in the soil in which they were grown. Whole grains and brewer's yeast are also notable sources of selenium, especially when they come from selenium-rich soils.

Symptoms and consequences of selenium deficiency

A selenium deficiency can lead to a range of symptoms and serious diseases. Among the clinical signs observed are increased fatigue, muscle weakness, and greater susceptibility to infections. In the long term, selenium deficiency can lead to diseases such as Keshan disease, an endemic form of cardiomyopathy, and Kashin-Beck disease, a chondrodystrophy observed in China where soils are poor in selenium. Low selenium concentration is also linked to reduced male fertility, worsening of symptoms of viral diseases such as HIV, and an increased risk of developing certain cancers such as prostate cancer. Furthermore, selenium deficiency can contribute to cognitive disorders, such as depression, anxiety, and confusion, as well as imbalances in thyroid hormone metabolism, particularly in the presence of iodine deficiency

Diagnosis of deficiency and recommended dosages

The diagnosis of selenium deficiency is mainly based on blood tests that measure plasma selenium concentration and glutathione peroxidase activity. Recommended daily intakes of selenium vary by age, sex, and health status, but are generally between 55 and 70 µg per day for a healthy adult. However, in specific contexts such as chronic disease or physiological stress, higher intakes may be necessary. It is essential to consult a healthcare professional to assess the need for supplementation.