The need for Oyster Shell Calcium 500 Mg Supplements Plus Vitamin D can be dependent on many factors including heredity, diet, exercise and lifestyle. Calcium is the primary mineral responsible for strong bones. The body also uses Calcium for proper muscle contraction and nerve function - and obtains this Calcium mainly from the bones. 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 health. Calcium also plays a role in muscle contractions and nerve impulses.