What is the role of vitamin D in the human body?

Like all steroid hormones, vitamin D is involved in the genetic regulation of the production of proteins and enzymes which are essential for wellness and prevention. Vitamin D promotes calcium absorption and maintains blood levels of calcium and phosphate for proper bone development and muscle action. Some of the other roles of Vitamin D are assistance in the regulation of cell growth, immune function, neuromuscular action, and regulation of inflammation. It assists the action of insulin and has been shown to have a significant role in cancer prevention. Many cells have Vitamin D receptors and many genes are influenced by the action of Vitamin D. In fact, it has been estimated that the human genome has over 2700 binding sites for Vitamin D. from http://www.vitamindcouncil.org/about-vitamin-d/what-is-vitamin-d/) This is why being deficient in Vitamin D can lead to increased risk of many diseases, and, conversely why being sufficient in Vitamin D is essential for wellness and prevention.