As an essential trace element, selenium (Se) plays a tremendous role in the functioning of the human organism being used for the biosynthesis of selenoproteins (proteins containing one or several selenocysteine residues). The functions of human selenoproteins in vivo are extremely diverse. Many selenoproteins have an antioxidant activity and, hence, play a key role in cell antioxidant defense and maintenance of redox homeostasis, which accounts for their involvement in diverse biological processes, such as signal transduction, proliferation, cell transformation and aging, ferroptosis, immune system functioning, etc. One of the critical functions of selenoenzymes is participation in the synthesis of thyroid hormones regulating basal metabolism in all body tissues. Over the last decades, optimization of population Se intake for prevention of diseases related to Se deficiency or excess has been recognized as a pressing issue in modern healthcare worldwide.
Keywords: antioxidants; selenium; selenocysteine; selenoproteins.