Calcium is a chemical element that is essential for living organisms, including humans. It is the most abundant mineral in the body and vital for good health. Your body needs calcium to build and maintain strong bones. Your heart, muscles, and nerves also need calcium to function properly. Some studies suggest that calcium, along with vitamin D, may have benefits beyond bone health: perhaps protecting against cancer, diabetes, and high blood pressure. Your body doesn’t produce calcium, so you must get it through other sources. Calcium can be found in a variety of foods, including dark green leafy vegetables, such as broccoli and kale.