Vitamin D is a fat-soluble vitamin that regulates the absorption of calcium and phosphorus as well as facilitates normal immune system function. This vitamin is an essential nutrient important for strong bones.
Vitamin D can come in several forms. The two major forms are vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol).The recommended form of vitamin D for supplementation is cholecalciferol.
Cholecalciferol is metabolized to its active form, calcitriol, which increases the body’s absorption of calcium and phosphorus.