Discovered by a Swedish chemist in 1817, selenium became an area of scientific interest in the 1950s, and is now recognized as an essential trace element for the human body. Trace elements are minerals present in small amounts in living tissues with various important functions. A total of 14 trace elements are known, including iron, zinc, iodine, copper, manganese, aluminum, lead and fluorine.

Selenium can only be obtained through diet or supplementation. Acting as a powerful antioxidant, it benefits the human body by protecting it from harmful free radicals, thereby ensuring the protective functions of the immune system.

Foods rich in selenium

  • Yeast
  • Seafood (oysters, tuna, halibut, sardines, crabs, etc.)
  • Meat (kidneys, liver)
  • Cereals
  • Brazil nuts

Other foods such as cereals, dairy products, cereals and eggs also contain adequate amounts of selenium.

Selenium is best consumed through a balanced diet. However, it may be appropriate to take a selenium supplement when the required level cannot be achieved through a proper diet. Although selenium supplements come in both organic and inorganic forms, research has shown that the organic form is more easily absorbed.

Signs of selenium deficiency

When a person does not consume enough selenium, the following signs and symptoms may occur.

  • Muscle weakness
  • Chronic fatigue
  • Hair loss
  • Infertility
  • Violation of immunity

Those with impaired digestion are at risk of malabsorption and an increased risk of deficiency.

Selenium and immunity

A strong and healthy immune system is an integral part of fighting any type of infection caused by bacteria or viruses. More than 30 selenoproteins are associated with selenium, which are responsible for a powerful antioxidant defense mechanism, an important function of the immune response that protects our body.

Antioxidants help prevent cell damage caused by excess free radicals and other types of oxidative stress. When oxidative stress can be minimized, healthy cells are less damaged, reducing the risk of disease or infection.

In addition, selenium has been found to have anti-inflammatory, antiviral, and antibacterial properties that significantly affect inflammation and the immune response. There are various studies that have shown a connection between selenium and viral infections and the thyroid gland, which will be discussed below.

Selenium and viral infections

Selenium deficiency is directly associated with an increased risk of viral infections. Decreasing levels of selenium in the body can lead to increased oxidative stress, which leads to increased inflammation. The most convincing evidence of the harmful effects of selenium deficiency comes from an area of China where the soil contains low levels of selenium. A large number of women and children have been found to have Keshan disease, a type of cardiomyopathy caused by a virus that can be prevented by taking selenium pills. This applies to groups of people who suffer from malnutrition, such as children and the elderly, who may be deficient in selenium and possibly more prone to infections.

A 2013 study published in the Journal of Nutrition looked closely at the link between selenium and two viruses, the Coxsackie virus and the flu. In the laboratory, mice were fed a selenium-deficient or sufficient diet for four weeks and then inoculated with Coxsackie virus B3 or an influenza strain. It was found that in the group that was on a diet with a deficiency of selenium, myocarditis – a dangerous heart infection – developed five times more often. In a group of selenium-deficient mice infected with the influenza virus, severe lung inflammation was found.

An additional study looked at the protective factors of selenium supplementation in mice against influenza and found that mice that received the supplement had higher survival rates than those that were deficient. This can once again be explained by the beneficial ability of selenium to kill viruses. I couldn’t find any human studies.

A 2004 study in the American Journal of Clinical Nutrition evaluated selenium and poliovirus. In the study, a group of adults with low blood levels of selenium received a placebo, 50 mcg, or 100 mcg of selenium daily for 15 weeks.

After 6 weeks, all groups received an oral polio vaccine. Then their blood was analyzed. The 50 mcg and 100 mcg supplemented groups had higher levels of selenium in their blood, as expected, and also showed a better immune response, helping to clear the poliovirus faster.

Selenium and the thyroid gland

Due to its antioxidant properties, studies have shown that selenium plays a key role in thyroid function and thyroid hormone production. In fact, in adults, the thyroid gland is the organ with the highest amount of selenium per gram of tissue. Low levels of selenium have been found to contribute to autoimmune thyroid diseases, including Hashimoto’s thyroiditis, hypothyroidism, thyroid cancer, and thyroid enlargement.

One popular study from 2002 looked at a group of patients with autoimmune thyroid disease. Some were given a placebo, while others were given 200 mcg of selenium supplements for three months. In the selenium group, thyroid peroxidase antibody levels were reduced from 100 percent to 63.6 percent, and ultrasounds showed less thyroid inflammation. This study provided strong evidence that selenium has a significant effect on thyroid health.

A 2016 article reviewed 16 different studies that measured serum thyroid peroxidase antibodies and thyroglobulin antibodies at 3-, 6-, and 12-month intervals in patients with Hashimoto’s thyroid disease. Of the two groups in the study, one received a thyroid drug called levothyroxine and selenium. The second group received only selenium. The results showed that the group that received both the drug and selenium showed a decrease in antibodies between three and 12 months. In the group that received only selenium supplements, antibody levels decreased over only three months. This suggests that selenium supplements in general help to optimize thyroid health.

Pregnant women with thyroid peroxidase antibodies are at high risk of developing thyroid dysfunction or hypothyroidism after delivery. The Journal of Clinical Endocrinology and Metabolism reports a 2007 study that found selenium supplements reduced the risk of postpartum thyroid problems. In a study, 151 women were given 200 mcg of selenium or a placebo around the third month of pregnancy. Those who took selenium were 20 percent less likely to develop thyroid abnormalities.

Fortunately, most prenatal vitamins contain selenium.


Selenium is involved in the synthesis (deiodinase – a selenium-containing enzyme) of thyroid hormones that contain iodine, therefore combating iodine deficiency is impossible against the background of selenium deficiency.
Selenium deficiency leads to the death of thyrocytes and replacement of thyroid parenchyma by connective tissue.
Taking into account the physiological role of selenium in the peripheral conversion of thyroxine into the active form of triiodothyronine, the simultaneous replenishment of iodine and selenium can reduce even a slight potential risk of unwanted consequences during iodine prophylaxis.

SYSTEM PHARM can offer you a reliable source of organic selenium – CEFOSELEN PURE – capsules #60 containing 100 mcg of organic selenium.

Let’s take care of health together

Everything will be UKRAINE💙💛