Calcium is required for strong bones, teeth and cardiac function. Calcium not only builds strong bones and teeth but maintains bone density and strength. It helps to regulate heartbeat, blood clotting and muscle contraction. As well as protecting the body from stress, magnesium works with calcium to provide help to these same body systems and participates in more than 50 different biochemical reactions. That's why magnesium is so important to bone formation, nerve and muscle transmittion, and energy production. The other minerals in this product, including potassium and zinc, are also in the citrate form for better absorption and utilization by the cells, and they provide a valuable contribution to bone strength.