The vitamin that the body produces when the body is exposed to UV light, and plays an important role in calcium and phosphorus metabolism
Vitamin D is one of the many essential vitamins needed by the body to function properly. It is one of the fat-soluble vitamins (others are vitamin A, vitamin E, and vitamin K). As a fat-soluble vitamin, it does not dissolve easily in water but it does so with nonpolar, fatty solvents. Vitamin D helps in the intestinal absorption of calcium, iron, magnesium, phosphate, and zinc. Without sufficient vitamin D in the body, rickets and osteomalacia may result. Rickets is a disease among children that arises when vitamin D is deficient, and characterized by imperfect calcification, softening, and distortion of the bones typically resulting in bow legs. Osteomalacia is the softening of the bones caused by lack of calcium and vitamin D. Deficiency of vitamin D is called hypovitaminosis D whereas the toxicity caused by the ingestion of large doses of vitamin D is referred to as hypervitaminosis D.
There are different vitamers of vitamin D. These are Vitamin D1, ergocalciferol (vitamin D2), cholecalciferol (vitamin D3), 22-dihydroergocalciferol (vitamin D4), and sitocalciferol (vitamin D5). The two major vitamers of vitamin D though are the ergocalciferol and the cholecalciferol.