The Role of Selenium in Supporting Glutathione Peroxidase Activity

Biochemical Relationship Between Selenium and Glutathione Peroxidase

Selenium is incorporated into selenoproteins, with glutathione peroxidase being one of the most important selenium-dependent enzymes in the body 1
Glutathione peroxidase catalyzes the reduction of hydrogen peroxide (H₂O₂) to water via the oxidation of glutathione (GSH) to glutathione disulfide (GSSG), thereby protecting cells from oxidative damage 3

Clinical guidelines recommend selenium supplementation at doses of 7 μg/kg/day in preterm infants, 2-3 μg/kg/day in term infants and children, and up to a maximum of 100 μg/day for routine supplementation 1, 2
Selenium status should be monitored regularly in patients on long-term parenteral nutrition and those with renal failure 1
Plasma selenium concentration and/or glutathione peroxidase activity in plasma or red blood cells can be used to assess selenium status 1

Glutathione peroxidase is part of a broader antioxidant defense system that includes other enzymes like superoxide dismutase and catalase 4
In conditions of oxidative stress, such as ischemia, inflammation, or chronic disease, adequate selenium levels are crucial for maintaining glutathione peroxidase activity 5
Selenium deficiency has been associated with various health conditions including hypertension, liver cirrhosis, osteopenia, immune disorders, and increased cancer risk, though causality has not been proven for all these associations 1
In preterm infants, low selenium status has been linked to bronchopulmonary dysplasia, highlighting the importance of adequate selenium for glutathione peroxidase function in vulnerable populations 1

Excessive selenium supplementation can lead to selenosis in adults, characterized by hair loss, nail changes, skin rash, tooth discoloration, and neurological symptoms 1
As selenium is excreted by the kidneys, doses exceeding dietary reference intakes should be avoided in patients with renal failure 6
Selenium status assessment should include both plasma selenium levels and glutathione peroxidase activity for a more complete picture 1
Relying solely on glutathione peroxidase activity as a marker of selenium status in preterm infants may be misleading due to effects of immaturity and oxygen exposure 1