Calcium is a mineral that plays an important role in bone health, as well as muscle and nerve function. It's most commonly associated with bone health, but it's also used to treat or prevent low blood calcium levels. Calcium is one of the most important minerals in the human body. It is also required for the normal functioning of the heart, muscles, and nerves. Calcium also plays an important role in blood clotting, hormone secretion and nerve function. Calcium deficiency can cause several health problems such as osteoporosis, high blood pressure, muscle cramps, kidney stones and seizures.