Cholecalciferol is a fat-soluble vitamin D2 compound produced in the skin from 7-dehydrocholesterol under UVB light or supplied in dietary supplements as vitamin D3 precursor. It is biologically inactive until converted in the liver and kidneys to calcitriol, the active form that regulates calcium and phosphate metabolism. In medical and nutritional contexts, it’s described as a vitamin D prohormone used to prevent or treat deficiency.
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