Figure 1.

Toxicodynamic of Vitamin D in High-Dose Intake: (1) Vitamin D from dietary meals and from the conversion of 7-DHC in the skin by UVB exposure is converted into vitamin D₂ and integrated into chylomicrons; (2) vitamin D in chylomicrons is transported to the liver or stored in adipose tissue; (3) the liver enzyme converts vitamin D₂ and vitamin D₃ to 25(OH)D, which is distributed in the blood; (4) it is then brought to the kidney, which is eventually activated to produce 1,25(OH)D; (5) finally, it is released into the circulation as a free form and binds to VDR.