Vitamin D is an essential element for the body. Its deficiency can lead to many types of physical problems. People with osteoporosis, diabetes, heart-stroke, reproductive problems, polycystic ovary syndrome, and obesity may have vitamin D deficiency. Vitamin D deficiency is currently a global health problem. One of the best sources of vitamin D is sunlight. Vitamin D is also found in various foods. However, 80 percent of the total needs of the body comes from vitamin D.