Calcium provides the building blocks that help keep bones and teeth strong and healthy. It also supports the health of the colon, heart, musculoskeletal and nervous systems. Magnesium helps to regulate calcium transport and stimulates the secretion of calcitonin, a hormone that aids in the influx of calcium into bone. Magnesium also works with ATP to produce the energy needed for most reactions in the body. It plays an important role in protein formation and healthy muscle function.