Calcium is an essential mineral. The body uses calcium for many important functions including building the structure of bone and teeth, the normal functioning of enzyme and hormone secretion, blood vessel contraction/expansion, and muscle contractions. The National Institute of Health estimates that many people consume less than half the amount of calcium they should for their body's needs. Possible benefits of calcium being studied include the slowing of tooth decay and the reduction of some symptoms of PMS. Research indicates that calcium intake is important starting from a young age. It is currently thought that the more bone mass you have early on, the more delayed the bone loss is in later years. Research is also showing that for the body to utilize calcium to its full potential, it needs to have enough magnesium (usually in a ration of 2:1) and vitamin D. People with certain malabsorption problems may be at greater risk for low calcium levels.* Recent research indicates that calcium citrate is one of the easiest forms of calcium for the body to absorb.