维生素D类是指合环戊氢烯菲环结构、并具有钙化醇生物活性的一大类物质。1919年Mellan发现了维生素D_2。20世纪60年代中叶发现维生素D的活性形式是1,25-(OH)_2-D_3。它作用于小肠、肾、骨等靶器官参与维持细胞内、外钙浓度,并调节钙磷的代谢。此外,它还作用于其它很多器官,如心脏、肌肉、大脑、造血器官和免疫器官,参与细胞代谢或分化的调 Vitamin D refers to the cyclopentadienyl phenanthrene ring structure and has a large group of calcified alcohol bioactive substances. Mellan discovered vitamin D in 1919. The active form of vitamin D found in the mid-1960s was 1,25- (OH) _2-D_3. It acts on the intestine, kidney, bone and other target organs involved in maintaining intracellular and extracellular calcium concentration, and regulate calcium and phosphorus metabolism. In addition, it also acts on many other organs, such as the heart, muscle, brain, hematopoietic organs and immune organs involved in cell metabolism or differentiation