Nature's Bounty, Calcium w/Vitamin D, 500 mg, 12 X 300 TabsProduct Description Calcium is the primary mineral responsible for strong bones.* The body also uses Calcium for proper muscle contraction, nerve function and heart function.* Vitamin D assists in Calcium absorption and maintaining a healthy immune system.* Because the body cannot produce Calcium, a balanced diet, regular exercise, healthy lifestyle choices and adequate intake of Calcium and Vitamin D can play a role in maintaining optimal bone