Vitamin D deficiency is when your body does not have enough vitamin D. Vitamin D is important to your body for many reasons:
- It helps the body absorb two important minerals—calcium and phosphorus.
- It plays a role in bone health.
- It may help to prevent some diseases, such as diabetes and multiple sclerosis.
- It plays a role in muscle function, including heart function.
If vitamin D deficiency is severe, it can cause a condition in which your bones become soft. In adults, this condition is called osteomalacia. In children, this condition is called rickets.