Thyroid
T3/T4 synthesis from tyrosine + iodine; deiodinase cofactors
Thyroid hormone sets the metabolic rate of every cell, and it's assembled from two raw materials: the amino acid tyrosine and iodine (T4 carries four iodine atoms, T3 carries three). But the hormone the thyroid mostly secretes — T4 — is largely inactive; a selenium-dependent enzyme (deiodinase) converts it to the active T3 in peripheral tissues. Zinc and iron support both synthesis and receptor sensitivity. This is why someone with adequate iodine can still feel hypothyroid if they're low in selenium: the factory works, but the activation step stalls.
How your supplements + diet feed this pathway right now — the cofactors driving it, where the gaps are, and your own lab readouts.
The load-bearing nutrients — if these are deficient, this pathway slows down. Click any to see daily targets, food sources, and supplements that supply it.
Nutrients that contribute to this pathway but aren’t the single load-bearing inputs.
Lab markers that report on how well this pathway is running. When one of these is out of range, this pathway is often where the upstream issue lives.
Save a lab session under My Journey → Biomarkers to see your own values for these.
Pathways that share a load-bearing cofactor with this one.