How Vitamin D3 Works in the Human Body
Vitamin D3 (cholecalciferol) functions more like a hormone than a traditional vitamin. After absorption, it is converted in the liver and kidneys into active forms that regulate calcium balance, immune response, muscle function, and cellular signalling throughout the body.
Its effectiveness depends not only on intake, but on absorption, conversion efficiency, and physiological compatibility. These processes explain why individuals respond differently to vitamin D3 supplementation.