The two organs that serve as sites of active vitamin D synthesis are the Kidneys and liver. Vitamin D is an example of a fat soluble vitamins together with vitamins A,E and K ( these are vitamins that travel with dietary fats through the blood stream, vitamins that are stored mostly in the liver and fatty tissues). The other group of vitamins are water soluble, such that they are readily excreted from the body, they are easily lost during food processing and preparation, and vitamins that include the vitamins B and vitamin C.