Product Details Jarrow FORMULAS® Vitamin D3 (cholecalciferol) is derived from cod liver oil and sheeps wool and is free of Vitamin A. Fat-soluble Vitamin D3 is converted by the kidneys into the hormone calcitriol, the activate form of Vitamin D3, which affects a variety of target tissues, including bone, intestine, muscle, brain, skin and immune cells. Calcitriol enhances calcium and phosphorous absorption and stimulates the synthesis of osteocalcin, an important structural protein in bone. Also, calcitriol is involved in proper cell differentiation (changing of cell function), including prostate cells. The information provided is accurate at the time of publication.Please note that we can display only image of one of the sizes per productas images for all sizes are not available. Product descriptions, images and ingredientsare believed to be accurate but may be changed at anytime by manufacturers.Please refer to the manufacturers website for the latest information.. HerbsPro.com offers nationally branded products that are produced according to pharmaceutical grade manufacturing standards at everyday low prices. Dont use unproven, unbranded products, which can pose serious risks to your health. Statements made, or products sold through this web site, have not been evaluated by the Food and Drug Administration. They are not intended to diagnose, treat, cure, or prevent any diseases. Consult a qualified health care practitioner before taking any substance for medicinal purposes.