Four different forms of calcium are used in the Reacted Calcium formula to maximize absorption in the body. Reacted Calcium provides three unique forms of highly-absorbed calcium to ensure maximum absorption of this important macromineral. While most calcium supplements use only a single source of calcium, which can easily overwhelm a single pathway of absorption and limit uptake, Reacted Calcium takes advantage of three unique pathways of absorption by providing calcium in the hydroxyapatite, di-calcium malate, and glycinate forms. In addition, Reacted Calcium includes vitamin D and phosphorus, both critical nutrients for bone mineralization and remodeling.