Side-by-side comparison of mechanisms, dosing, interactions, and stacking potential.
| Iodine (from Kelp or Potassium Iodide) | Selenium (Selenomethionine) | |
|---|---|---|
| Category | Minerals | Minerals |
| Standard Dose | 150-300 mcg daily (RDA: 150 mcg; upper range for optimization) | 200 mcg selenomethionine daily |
| Timing | Morning with food. | With meals. Can be taken any time of day. |
| Cycle Duration | ongoing | ongoing |
| Evidence Level | strong_human | strong_human |
Iodine is the essential substrate for thyroid hormone synthesis. Thyroid peroxidase (TPO) uses iodine to iodinate tyrosine residues on thyroglobulin, producing monoiodotyrosine (MIT) and diiodotyrosine (DIT), which couple to form T4 (3,5,3',5'-tetraiodothyronine) and T3 (3,5,3'-triiodothyronine). Iodine is concentrated by the sodium-iodide symporter (NIS) in the thyroid, breast tissue, gastric mucosa, salivary glands, and choroid plexus. Beyond thyroid function, iodine has direct antimicrobial properties, modulates immune function, and may play a role in breast tissue health via iodolactone-mediated apoptosis.
150-300 mcg daily (RDA: 150 mcg; upper range for optimization)
Morning with food.
ongoing
Selenium is incorporated as selenocysteine (the 21st amino acid) into 25 selenoproteins. Key enzymes: glutathione peroxidases (GPx1-4, reduce hydrogen peroxide and lipid hydroperoxides), thioredoxin reductases (TrxR1-3, maintain cellular redox balance), iodothyronine deiodinases (DIO1-3, convert T4 to T3 and regulate thyroid hormone metabolism), selenoprotein P (selenium transport and brain antioxidant), and selenoprotein W (muscle antioxidant). Selenium is essential for thyroid function, immune defense, reproductive health, and cancer chemoprevention.
200 mcg selenomethionine daily
With meals. Can be taken any time of day.
ongoing
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