In recent years, the importance of vitamin D has been thoroughly researched, and it has been found to be a critical vitamin to overall human health. It was once thought that a deficiency would have its impact only on the skeletal system, manifesting as rickets or osteomalacia. However, it has come to light that a suboptimal level of serum hydroxyvitamin D, known as an insufficiency, may contribute to a host of disease processes including cardiovascular disease, cancer, autoimmune diseases, and infections.