Calcium "600" Tablets (from Oyster Shell with Vitamin D3). Calcium is an essential mineral needed every day for proper health. 99% of the body’s calcium can be found in the bones. This mineral provides the building blocks that help keep bones and teeth strong and healthy. In addition, calcium helps to support the health of other systems in the body, including the heart, musculoskeletal and nervous systems. This formula contains Vitamin D3 to enhance the absorption of calcium. Adequate Calcium and Vitamin D as part of a healthful diet, along with physical activity, may reduce the risk of osteoporosis in later life.