According to scientific studies, the vitamin D3 (cholecalciferol) is the most bioavailable form of vitamin D. The active form of vitamin D amine by an organization involved in activation-ing various important biological processes such as: • the mobilization of calcium and phosphorus from bone tissue • the absorption of calcium and phosphorus from food-cations • the the thyroid and parathyroid gland • the function of the nervous system • the function of the immune system.