Selenium
Essential component of selenoproteins including glutathione peroxidases (reduces lipid peroxides) and thioredoxin reductase (recycles oxidised thioredoxin). Also required for T4 → T3 thyroid hormone conversion. L-selenomethionine: highest bioavailability form.
Mechanism
Selenium is incorporated as selenocysteine - the 21st amino acid - into 25 distinct selenoproteins. The most functionally critical are: glutathione peroxidases (GPx1-6), which reduce hydrogen peroxide and lipid hydroperoxides using glutathione as electron donor; thioredoxin reductases (TrxR1-3), which regenerate reduced thioredoxin to support cellular redox balance; and iodothyronine deiodinases, which convert T4 to the active T3 thyroid hormone.
L-selenomethionine - the organic form - has approximately 90% bioavailability compared to ~50% for inorganic sodium selenite. The organic form incorporates into tissue proteins (including skeletal muscle) as a body selenium reservoir, providing more stable tissue levels between doses.
Key Benefits
- Component of glutathione peroxidases - reduces lipid peroxides
- Required for T4 → T3 thyroid hormone activation
- L-selenomethionine: ~90% bioavailability vs ~50% for selenite
- Builds tissue selenium reservoir in skeletal muscle
- 55mcg = 100% NRV - within safe distance from upper limit
Selenium
100mcgL-Selenomethionine - organic, highest bioavailability
Any time of day with food. Organic selenomethionine has ~90% bioavailability vs ~50% for inorganic selenite. 55mcg targets the NRV without approaching the Upper Tolerable Intake (400mcg/day).