Before prescribing calcium, physicians should be aware of the calcium intake from the patient's diet. The total daily intake should be at least 1000 mg and not over 2.500 mg. Calcium recommendations , the 1999 recommendations from the National Academy of Science. NIH Consensus statement . If a supplement is prescribed, then it should be one with good dissolution.
Chewable tablets are a safe bet.
Because calcium is absorbed better with food, it should be given with meals. Also, calcium carbonate is an antacid, and it causes a rebound gastric acidity when given on an empty stomach. TUMS does not contain aluminum and it has only a very small amount of sodium and flavoring. Not all calcium preparations are absorbed equally, and one of the reasons is that they have different rates of dissolution. It is less expensive to manufacture calcium carbonate in a compact form that will not readily dissolve.