Bioclinic Naturals Vitamin D3 5000 I.U. is designed to address insufficient vitamin D levels in the blood. Vitamin D is a hormone now widely recognized to be important to many body systems and a large number of physiological processes, and it may also be one of the most common nutrient deficiencies in the world. Vitamin D is needed for intestinal calcium absorption, skeletal bone integrity as well as skeletal muscle strength and function, and has been associated with overall physical fitness. It is critical for healthy immune function, and may reduce the risk of infection, especially respiratory tract infections. Essentially every tissue in the body has a vitamin D receptor, making it hard to overestimate its importance. These statements have not been evaluated by the Food and Drug Administration and this product does not claim to prevent, treat, cure or diagnose any disease or deficiency.