Selenium is a trace element that is naturally present in many foods, and available as a dietary supplement. In order to stay healthy, the body needs Selenium nutrients. Selenium is important for many functions including reproduction, thyroid gland function, DNA production, and protecting the body from damage caused by free radicals and from infection..

There are two form of Selenium: inorganic and organic. Both forms can be good dietary sources of selenium. Soils contain inorganic selenium that plants accumulate and convert to organic forms,

Most selenium is in organic form, present in animal and human tissue. Majorly stored in skeletal muscle contributing approximately 20 to 50% of the total selenium storage.  

Sources of Selenium


The richest food sources of selenium are Brazil nuts, sea-foods, and organ meats. Other sources of selenium are muscle meats, cereals and grains, and dairy products. The major food sources of selenium in diet are breads, grains, meat, poultry, fish, and eggs.

The amount of selenium in a plant-based food depends on the amount of selenium in the soil. The following factors contribute to the selenium content in the soil

  1. Soil pH,
  2. Amount of organic matter in the soil,
  3. The form that is amenable to plant uptake.

The selenium content of soil affects the amounts of selenium in the plants that animals eat, so the quantities of selenium in animal products also vary.

Dietary Supplements

Selenium is available in many multivitamins or multimineral supplements and as a stand-alone supplement. Selenium is present in supplements are often in the forms of selenomethionine or of selenium-enriched yeast which are grown in a high-selenium medium or as sodium selenite or sodium selenate. The human body absorbs more than 90% of selenomethionine but only about 50% of selenium from selenite.


Selenium Deficiency

Selenium deficiency leads to many biochemical changes that might predispose people who experience additional stresses to develop certain illnesses.  Selenium deficiency along with combination of second stress due to viral infection leads to Keshan disease, which is a type of a type of heart disease

Selenium deficiency is also a cause of infertility in males and might play a key role in Kashin-Beck disease, which is a type of osteoarthritis that causes pain, swelling, and loss of motion in your joints. Selenium deficiency could exacerbate iodine deficiency, potentially increasing the risk of cretinism in infants.

Health benefit of Selenium

Diseases and disorders in which selenium might play a role: cancer, cardiovascular disease, cognitive decline, thyroid disease, immune function and reduction of asthma symptoms.


Selenium has effects on DNA repair, apoptosis, as well as on endocrine and immune systems as well as other mechanisms, including its antioxidant properties, selenium might play a role in the prevention of cancer.

Epidemiological studies have suggested an inverse association between selenium status and the risk of colorectal, prostate, lung, bladder, skin, esophageal, and gastric cancers.

Cardiovascular disease

Selenium protein is effective in prevention of the oxidative modification of lipids, reduction of inflammation and prevention of platelets from aggregating. For these reasons, it has been reported that selenium supplements could reduce the risk of cardiovascular disease or deaths associated with cardiovascular disease.

Cognitive decline

Serum selenium concentrations decline with age. Marginal or deficient selenium concentrations might be associated with age-related declines in brain function, possibly due to decreases in selenium’s antioxidant activity.

Researchers have evaluated that taking an antioxidant supplement containing selenium reduces the risk of cognitive impairment in elderly people.


Thyroid disease

Selenium concentration is higher in the thyroid gland than in any other organ in the body, and, like iodine, selenium has important functions in thyroid hormone synthesis and metabolism.

Immune System


Selenium plays a key role in the immune health. This antioxidant lowers oxidative stress in your body, which reduces inflammation and enhances immunity.

Studies have reported that increased selenium levels are associated with enhanced immune response. On the other hand, deficiency has been shown to harm immune cell function and may lead to a slower immune response.

Studies have also associated deficiency with an increased risk of death and disease progression in people with HIV, whereas supplementation of selenium has shown fewer hospitalizations and an improvement in symptoms for these patients. Furthermore selenium supplements may help strengthen the immune system in people with influenza, tuberculosis, and hepatitis C

Reduction of asthma symptoms

Asthma has been linked 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 also suggests that people who have asthma have lower blood levels of selenium.

One study showed that asthmatic patients with higher levels of selenium had better lung function than those with lower levels. Selenium supplements may also reduce asthma-related symptoms.