Selenium is a micronutrient found in brazil nuts, garlic and shellfish that increases immunity, boosts antioxidant activity (specifically the body’s master antioxidant glutathione), and plays a key role in maintaining healthy thyroid function. Selenium acts like a mechanic within the body: it goes into the nucleus of the cells where the DNA is stored and looks for damage. It attaches to protective antioxidants like glutathione and then works to reduce and repair DNA damage (which left uncontrolled could lead to cancerous cell mutation and tumor growth).


According to studies, selenium is effective at reducing the risk of cancer incidence, cancer caused mortality, and severity of cancers specifically in the liver, prostate, colorectal and lungs (Fleet, 1997). It does this by activating ‘selenoproteins,’ which distribute selenium from the liver all around the body, and help antioxidants do their job. There is evidence that selenium can not only help cut cancer risk but can also contribute to slowing down existing cancer progression and tumor growth. (Rayman, 2005). Lastly, a 2016 study published in The American Journal of Clinical Nutrition shows that the highest levels of blood selenium/selenoprotein P are associated with a decreased risk of developing liver cancer.


Selenium is essential for the conversion of thyroid hormones (T4 to T3), as deiodinase enzymes (which remove iodine atoms from T4 during conversion) are selenium dependent. Several research studies have demonstrated the benefits of selenium supplementation in treating autoimmune thyroid conditions. One study found that selenium supplementation had a significant impact on inflammatory activity in thyroid specific autoimmune disease and reducing inflammation may limit damage to thyroid tissue. Another study which followed patients for 9 months, found that selenium supplementation reduced thyroid peroxidase antibody levels in the blood, even in already selenium sufficient patients.


Researchers working with the flu virus discovered that animals deficient in selenium were more susceptible to infectious diseases. When animals with a selenium deficiency were contaminated with the flu virus, the virus was able to evolve and mutate into a far more virulent form when it was passed on to the next animal.


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