Is Citracal or Caltrate better

Calcium carbonate (Caltrate) should be taken with meals since it requires stomach acid to dissolve and absorb. Also, calcium carbonate has the most calcium per pill (40%), therefore you need to take fewer pills. In some people, calcium carbonate causes constipation. Calcium citrate (Citracal) can be absorbed on an empty stomach and is not as dependent on stomach acid for absorption. However, it has less calcium per pill (20%), so you have to take more pills. It does not cause constipation.