Selenium is a trace mineral that needs to be taken with food daily, but only in very small amounts (50 micrograms or less).
Functions of Selenium
- Prevention of oxidative stress. Although oxygen is essential for maintaining the life of people, it is a substance that, when it is in the body, it can make molecules overly reactive and they can damage cell structures around them. In chemistry, this imbalanced situation involving oxygen is called oxidative stress . Selenium helps prevent oxidative stress by working together with a group of other nutrients with similar functions. This group includes vitamin E, vitamin C, glutathione, selenium and vitamin B3.
- Supporting the thyroid gland. In addition to iodine, selenium is essential for maintaining the function of the thyroid gland. Selenium is essential for the thyroid gland to produce the active form of its hormone (release of thyroid hormones, called T3), and also helps regulate the amount of hormone that is no longer manufactured.
- Prevention of cancerous diseases . It has been shown that selenium induces DNA repair and synthesis in damaged cells, helping to inhibit the proliferation of cancer cells and induce their apoptosis / cycle of self-destruction, in which the body removes abnormal cells /. Selenium interacts with many proteins, including glutathione peroxidase, which is particularly important for protection against cancer .
Deficiency of selenium
Symptoms of prolonged selenium deficiency occur in two areas of the body, namely the heart and joints. Regarding the heart, the most characteristic symptom is a specific disease called that can be prevented by increased intake of selenium. This disease includes cardiac arrhythmias and loss of cardiac tissue. As regarding the joints, there is also a specific disease called the Kashin-Beck disease. It is associated with degeneration of the connective tissue.
In severe deficiency of selenium, accompanied by severe general malnutrition, symptoms may include weakness or muscle pain, loss of color of hair and skin and whitening of the nail base.
In some foods, where a large percentage of selenium is contained in water-soluble form, contact with water can lead to a large loss of selenium. For example, when cooking beans, they will lose 50% of their initial content of selenium. In animal foods, loss of selenium in cooking is minimal.
Nutritional deficiency is the most common cause of deficiency of selenium. As the content of selenium in plants is highly dependent on the content of selenium in the soil, scientists have identified various areas in the world where selenium deficiency is very common.
Glucocorticoids are widely used anti-inflammatory drugs based on the prototype of a substance called cortisol. All drugs of this type can reduce the supply of selenium to the body.
Selenium is indirectly responsible for maintaining supply to the body of three other nutrients, namely vitamin C , glutathione and vitamin D. A deficiency of iron and copper also increases the risk of selenium deficiency.
On the other hand- nausea, vomiting, hair loss and skin lesions may be symptoms of selenium toxicity. Selenium levels needed to trigger these symptoms of toxicity are not usually given with food as selenium-rich foods contain about 30 to 50 micrograms. High intake of selenium is more likely in case of selenium toxicity of the food itself.
The National Academy of Sciences of the United States sets an admissible upper limit (UL) for intake of 400 micrograms of selenium per day for men and women 19 years and older.
Benefits of Selenium
Selenium can play an important role in the prevention and / or treatment of the following diseases: acne , asthma , cervical dysplasia, colorectal cancer, AIDS, infertility in men, Kashin Beck disease, Kashin disease, multiple sclerosis, ovarian cysts, disease, Parkinson's , psoriasis , rheumatoid arthritis , cataracts , stomach cancer and others.
Selenium can be found as a food additive in one of two basic forms: chelated or non- chelated. From the chelated form, selenomethionine and selenocysteine are most widely available. In the non- chelated form most widely available are sodium selenite and sodium selenate.
Sources of Selenium
Brazil nuts are the most concentrated source of selenium. When grown under ideal soil conditions young mushrooms, shiitake mushrooms, cod, shrimp, snapper, tuna, halibut, beef liver and salmon are other excellent sources of selenium.