Vitamin D Activation
Skin/liver/kidney 2-step hydroxylation — magnesium-dependent
The 'vitamin D' you get from sun or a supplement is inactive — it has to be switched on in two steps. The liver first hydroxylates it to 25-OH vitamin D (the form measured on a blood test), and the kidney then converts that to the active hormone, calcitriol. Both hydroxylation steps are magnesium-dependent enzymes, which is why supplementing vitamin D while magnesium-deficient often fails to raise the active hormone — you can fill the tank but can't turn the key. Vitamin K then works alongside activated vitamin D to direct the absorbed calcium into bone rather than soft tissue.
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.
Pathways that share a load-bearing cofactor with this one.