| Customization: | Available |
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| CAS No.: | 67-97-0;8024-19-9;8050-67-7 |
| Formula: | C27h44o |
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Vitamin D is a fat-soluble vitamin that regulates calcium homeostasis and is vital for bone health. The two most prominent forms of vitamin D are ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3). Vitamin D3Vitamin D3 can be destroyed by exposure to ultraviolet (UV) light and by peroxidation in the presence of rancidifying polyunsaturated fatty acids (PUFA). Like vitamins A and E, unless vitamin D3 is stabilized, it is destroyed by oxidation, which is increased by heat, moisture and trace minerals. Vitamin D3 is absorbed from the intestinal tract in association with fats, as are all the fat-soluble vitamins. Like the others, it requires the presence of bile salts for absorption. Cholecalciferol plays an essential role in calcium and phosphorus metabolism in animals. In particular, cholecalciferol is required for the absorption of calcium from the gastro-intestinal tract and for the calcification of growing bone tissue. Before cholecalciferol can perform these metabolic functions it is first converted to 25-hydroxycalciferol (25-HCC) in the liver, which in turn is converted to the physiological active form 1,25-dihydroxycalciferol (1,25-DHCC) in the kidney. It is 1,25-DHCC which acts on the respective target tissues and is responsible for the synthesis of the calciumbinding protein in the intestinal epithelial cells. Additional functions which have been ascribed to 1,25-DHCC include: the conversion of organic phosphorus to inorganic phosphorus in bone, the resorption of phosphate and amino acids from the kidney tubules, the maintenance of blood calcium level, and the deposition and oxidation of citrate in bone.
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