MARINCAL-D 500/200 is a tablet containing 500 mg of elemental calcium (derived from coral calcium) and 200 IU of vitamin D3 (cholecalciferol). 1 This combination medicine is used to treat and prevent calcium and vitamin D deficiency, as well as conditions like osteoporosis, osteomalacia, and tetany. 2 The coral calcium source may offer better absorption, and vitamin D3 aids in the body's absorption of calcium, contributing to the maintenance of healthy bones and teeth. It is often recommended as a supplement during periods of increased need, such as childhood growth, pregnancy, breastfeeding, and in elderly individuals