Vitamin D is a group of fat-soluble secosteroids responsible for increasing intestinal absorption of calcium, magnesium, and phosphate, and multiple other biological effects.
Cholecalciferol is converted in the liver to calcifediol. Calcifediol is further hydroxylated by the kidneys to form calcitriol. Vitamin D in its active form calcitriol effects via nuclear receptors in multiple locations. Calcitriol circulates as a hormone in the blood and it has a significant role in the absorption of calcium and phosphate and supporting the healthy growth and regeneration of bone. It has effects on some cell growth, neuromuscular and immune functions, and reduction of inflammation.