Antioxidant Action of Selenium and Selenoproteins

Antioxidants. Several selenoproteins play important roles as antioxidant enzymes in the protection of the cells and the mitochondria against the oxidative damage caused by harmful free radicals. Prominent among the antioxidant seleno-enzymes are the glutathione peroxidases and the thioredoxin reductases [Alehagen 2022].

Professor Urban Alehagen
Professor Urban Alehagen, the lead researcher on the KiSel-10 Study, estimates that a daily selenium intake of 110-150 mcg per day is necessary to achieve optimal expression of selenoprotein P, one of the most important selenoproteins in the plasma and the main transporter of selenium in the blood [Alehagen 2022].
Note: Oxidative stress is the bio-medical term for an imbalance in the relationship of 1) harmful free radicals, mostly of the reactive oxygen species, and 2) protective antioxidants, which should neutralize the harmful free radicals.

In many regions of the world, notably in much of Europe and the Middle East, there is selenium-poor soil and selenium-poor foodstuffs. In Sweden, for example, the average daily intake of selenium among senior citizens
is approximately 35 mcg/day, well below the amounts (110–150 mcg/day) needed for an optimal expression of the selenoprotein antioxidants [Alehagen 2022].
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Impact of Selenium Status on Ageing

Selenium is an essential trace element. Essential means that sufficient selenium is necessary for normal cell functioning and that our bodies cannot synthesize selenium for us. We must get it from our diets. Trace element means selenium is a micronutrient that is needed in very small quantities, in microgram quantities. It may be an important element to slow the ageing process.

Elderly couple
Selenium as a component in protective enzymes helps to keep us healthier longer in life. It helps to suppress oxidative stress and to decrease inflammation, to remove misfolded proteins, to decrease DNA damage, and to promote telomere length.

Sufficient selenium status plays an important role in the prevention of cardiovascular diseases, inflammation, and infections. Prof. Margaret P. Rayman, University of Surrey, estimates that serum/plasma selenium status of around 125 mcg/L is optimal for human health [Rayman 2020].

The beneficial work of selenium in the cells and tissues is done by selenoproteins that contain the amino acid selenocysteine in the active center. Among the selenoproteins known to have an antioxidant effect in the body are the glutathione peroxidases (GPX1-4 and GPX6) and the thioredoxin reductases (TXNRD1-3) [Alehagen 2021]. read more