Selenium
From IKE
to explain an antioxidant function for selenium in relation to its role in glutathione peroxidase
Contents |
Basics
- An essential metal
- functions as an antioxidant that works in conjunction with vitamin E
- Several selenoproteins are involved in reducing oxidant stress:
- Glutathione peroxidase
- Thioredoxin Reductase
- Selenoprotein P
- Selenoprotein W
- Some effects are explained by its role in glutathione peroxidase in that its role overlaps that of vitamin E
- Some forms of liver necrosis in rats can be cured by either selenium or vitamin E
- 2 glut-SH + H2O2 = 2H2O + glut-S-S-glut
- Many other effects remain to be explained in terms of Se-proteins
- most Se is bound to proteins (Se-proteins)
Role
- ~5-20 mg is present in the body
- wide variation in intake 0.05-0.5 mg/day
- Highest concentrations are in RBC, liver, spleen
- Absorbed throughout the small intestine
- Excreted:
- in pancreatic secretions (enzymes)
- across the gut wall
- by kidney after metabolism
Toxicity
- Selenium has a narrow window of effectiveness, above which toxic symptoms can ensue
- Toxic effects in cattle and sheep in some countries ("blind staggers")
- In humans, toxic effects include damage to liver and muscle but are rare
- For toxicity, 25-50 times the RDI has to be consumed
