Category: vitamin
Aliases: Cholecalciferol, Vitamin D3, vit-d3, vitamin-d3, cholecalciferol
Cholecalciferol is the pro-hormone produced from 7-dehydrocholesterol by UVB in skin. Sequentially hydroxylated (see [[vitamin_d_metabolism]]) in liver (CYP2R1 → 25-OH-D / [[calcifediol]]) and kidney (CYP27B1 → 1,25-(OH)₂D / [[calcitriol]], the active hormone). Calcitriol binds VDR to regulate ~500 genes controlling intestinal Ca²⁺ absorption, bone remodelling, and innate-immune LL-37 / CAMP expression. [[magnesium]] is a cofactor for both hydroxylation steps.
PO: 360h