Healthy With Age

As you probably know, all vitamins come in several forms. Vitamin D, for example, has D1 through D5 variations, and most of these have at least a couple of different possibilities for their chemical composition. Vitamin D3 is available in three different forms:

Cholecalciferol: Is an inactive form of vitamin D3, similar in structure to testosterone, cholesterol and cortisol.

Calcifediol: This is the form that is measured during a blood test and is the hydroxylated form of cholecalciferol. 

Calcitriol: Once calcifediol has been hydroxylated, it turns into calcitrol, which is the most active vitamin D3 hormone