Calcium from oyster shell is popular among people who are looking for a natural source of calcium to support bone health. Natural food sources of calcium can be found in green leafy vegetables, meat, dairy, and legumes. But oyster shell is a particularly valued source of calcium because it s a natural source with a high percentage of elemental calcium per serving. Calcium is well-known for its key role in bone health. Calcium may also help maintain heart rhythm, muscle function, and more. Our oyster shell calcium also contains vitamin D3, which may be important for the metabolism and absorption of calcium in the body. Vitamin D3 may also help in maintaining optimal energy levels and a healthy immune system.