Selenium Deficiency: Most Effective Dietary Supplements

Selenium is an essential trace element that plays a key role in protecting against oxidative stress. It is particularly important for the integrity of cell membranes, due 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 contributes to detoxifying the body by binding to certain heavy metals and xenobiotics, forming selenium-metal complexes that are easier to eliminate. Selenium also plays a role in regulating thyroid hormones and supports the immune system. It is found in the body in two main forms: selenomethionine, present in plants, and selenocysteine, mainly from animal proteins. The most active and directly catalytic forms are the mineral forms, such as sodium selenite.

Food 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 like garlic and broccoli, although their content heavily depends on the amount of selenium present in the soil where they are 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 serious symptoms and diseases. Among the observed clinical signs, increased fatigue, muscle weakness, and greater susceptibility to infections are noted. Long-term selenium deficiency can lead to diseases such as Keshan disease, a form of endemic cardiomyopathy, and Kashin-Beck disease, a type of chondrodystrophy observed in China where soils are low in selenium. Low selenium concentration is also linked to reduced male fertility, worsening of symptoms of viral diseases like HIV, and an increased risk of developing certain cancers such as prostate cancer. Moreover, selenium deficiency can contribute to cognitive disorders, such as depression, anxiety, and confusion, as well as imbalances in the metabolism of thyroid hormones, particularly in the presence of iodine deficiency.

Diagnosis of Deficiency and Recommended Dosages

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