Calcium is crucial to maintain life. Just about every cell in the body, including those in the heart, nerves and muscles, relies on calcium to function properly. Bones require calcium to maintain their strength. Calcium is found in three places in the body, the skeleton and teeth, cells and blood. Because calcium is so important, the body has a carefully regulated system to ensure that a good supply is always- and immediately-available. The body does it in three ways: it absorbs calcium directly from the food we eat, it takes calcium from our bones if there is not enough available. When this happens, the bones become less dense and more fragile. It slows down the amount of calcium that leaves the body in the urine by returning some to the blood stream where it remains available to organs and cells. The main goal of good calcium nutrition is to maintain an adequate supply so that our bodies do not have to dip into our only calcium reservoir- our bones.