Description

Vitamin D3 is a fat-soluble precursor for steroid-like hormone. It is transformed into the biologically active molecule 1,25 dihydroxy vitamin D. After being synthesized in the skin or absorbed (in chylomicrons) from the gastrointestinal (GI) tract, most vitamin D is bound to specific carrier proteins in the blood (vitamin D-binding protein [DBP] and albumin) and transported to the liver. In the liver, vitamin D is hydroxylated by the enzyme 25-hydroxylase (CYP2R1) to become 25(OH)D. 25(OH)D is the major circulating form of vitamin D, testing of 25(OH)D help assessing the total-body vitamin D status.

Vitamin D is a major contributor for maintaining bone health, and vitamin D deficiency is also related with immunomodulation, diabetes, kinds of cancer, cardiovascular disease, autoimmune disease, congenital immune disease.