The Malta Independent 19 June 2021, Saturday

The secret of Selenium

Monday, 17 May 2021, 07:36 Last update: about 2 months ago

Dr Michelle Muscat

Selenium is an essential trace mineral that is named after the moon goddess of legend. It is naturally found in numerous foodstuffs.

Brazil nuts are an example of a well-known excellent selenium source and other sources include yellowfin tuna, sardines and ham.

Certain areas may have soil that is more selenium rich than others. Selenium exists either as an inorganic or organic variety. The form found in the soil is inorganic and is converted by plants to the organic form such as selenomethionine and selenocysteine.


Selenium is also found in dietary supplements and has myriads of health benefits. Selenium is vital in the human body in relation to being a constituent of selenoproteins. It is an ‘enzyme helper’ or cofactor, it reduces oxidative stress and plays a role in thyroid hormone health. Overall it promotes healthier metabolism, boosts immunity and reduces damage by free radicals. The Recommended Dietary Allowance (RDA) for selenium in adults is 55 mcg per day, while the recommended requirement is slightly increased for pregnant or lactating females.

It is reported that selenium may even be beneficial in the preventing certain cancers.  Selenium also detoxifies mercury.

Some current studies have associated selenium deficiency as a potential contributing factor for novel coronavirus disease 2019 (Covid-19) risk. Some researchers currently suggest ensuring adequate levels of micronutrients may help mitigate against the adverse clinical outcomes of Covid-19. Selenium, Vitamin D and Vitamin C have been suggested to have beneficial effects in the setting of coronavirus.

Selenium deficiency has previously been associated with biochemical changes and diseases such as Keshan and Kashin-Beck disease. Keshan disease affects the heart, it is a so-called cardiomyopathy whereas Kashin-Beck disease affects the joints. Individuals on long-term haemodialysis and those living with HIV are more likely to be selenium deficient. A chemotherapeutic agent known as cisplatin may cause reduction in selenium.

Selenium can be easily supplemented by having a couple of brazil nuts in moderation. Due to their high content of phytic acid which binds minerals, some suggest they can be soaked in water overnight to mitigate this. Alternatively, you may take eat seafood such as shellfish, yellowfin tuna, sardines, shrimps or salmon. Other foodstuffs such as chicken, beef liver, turkey, eggs, roasted ham and others can contribute to your selenium intake.

Excessive selenium intake, on the other hand, can lead to a disease known as selenosis. Hence, one requires the right amount of selenium without either deficient or excessive intake. Like many other things in life, balance is key.

Obviously, selenium is no replacement for all other preventive measures such as physical distancing, hand washing and other hygienic measures.

Although more studies are needed with larger cohorts to ascertain the impact of any decrease in risk or severity reduction of having adequate selenium levels on Covid-19, as well as its exact role in novel coronavirus matters; even before Covid-19 came along to rock our world it was already advisable to have adequate levels of selenium, that is, neither in deficiency or excess.   


Dr Michelle (k/a Mikhaila) Muscat is a medical doctor and Consultant Chemical Pathologist in charge of Toxicology Labs.


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