The major function of vitamin D is the maintenance of blood serum concentrations of calcium and phosphorus by enhancing absorption of these minerals in the small intestine. Vitamin D deficiency can lead to abnormalities in calcium and bone metabolism such as rickets in children or osteomalacia in adults. More recent research has linked adequate vitamin D to support for other health issues including: cardiovascular health, muscle aches, normal blood sugar levels, immunity, mood, mental health, gum health and skin health.