Abstract
Selenium (Se) is an essential dietary trace element that plays an important role in the prevention of inflammation, cardiovascular diseases, infections, and cancer. Selenoproteins contain selenocysteine in the active center and include, i.a., the enzymes thioredoxin reductases (TXNRD1–3), glutathione peroxidases (GPX1–4 and GPX6) and methionine sulfoxide reductase, involved in immune functions, metabolic homeostasis, and antioxidant defense. Ageing is an inevitable process, which, i.a., involves an imbalance between antioxidative defense and reactive oxygen species (ROS), changes in protein and mitochondrial renewal, telomere attrition, cellular senescence, epigenetic alterations, and stem cell exhaustion. These conditions are associated with mild to moderate inflammation, which always accompanies the process of ageing and age-related diseases. In older individuals, Se, by being a component in protective enzymes, operates by decreasing ROS-mediated inflammation, removing misfolded proteins, decreasing DNA damage, and promoting telomere length. Se-dependent GPX1–4 and TXNRD1–3 directly suppress oxidative stress. Selenoprotein H in the cell nucleus protects DNA, and selenoproteins residing in the endoplasmic reticulum (ER) assist in the removal of misfolded proteins and protection against ER stress. In this review, we highlight the role of adequate Se status for human ageing and prevention of age-related diseases, and further its proposed role in preservation of telomere length in middle-aged and elderly individuals.
Highlights
Ageing has been described as an imbalance between damage inflicted through the antioxidative defenses of an organism and the harmful production of reactive oxygen species (ROS) [1]
Se is absorbed into the body by Se-related transporters in the distal part of the small intestine, and after uptake in the liver it may either enter the methionine pool, which may serve as a long-term storage for Se, or it is metabolized to hydrogen selenide and incorporated into selenoprotein P (SELENOP)
Biological ageing is known as a complex process comprised of molecular heterogeneity, molecular damage, changes in immune function and metabolic imbalance, along with increased susceptibility to diseases and environmental stressors
Summary
Ageing has been described as an imbalance between damage inflicted through the antioxidative defenses of an organism and the harmful production of reactive oxygen species (ROS) [1]. Oxidative damage to biomacromolecules (proteins, nucleic acids, and lipids) accompanying harmful ROS production can represent a condition for developing age-related diseases [2], whereas a programmed part of the ageing process may proceed independently from oxidative stress or external exposures [3]. Biomolecules 2021, 11, 1478 the risk of developing age-related diseases [7,8]. In the EVA study, low levels of Se appeared to decrease human life expectancy by increasing vulnerability to different diseases, suggesting blood Se values to represent a longevity index in an aged population [9]. In COVID-19, which seems to be an age-related disease as the lethality increases strongly with age [16], a low selenium status was associated with an unfavorable outcome [17]. The aim of the present review is to highlight the importance of an adequate selenium status for healthy aging
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