Calcium supplements: practical considerations.

The preferable source of calcium is a balanced diet, but medicinal supplements are sometimes necessary if patients are to reach desired intakes. A divided dose regimen (4x/d; i.e., with meals and at bedtime) results in substantially greater absorption of a supplement than does 1x/d dosing. However, differences in chemical solubility between supplement preparations are of little importance, with calcium carbonate preparations, for example, being absorbed as well or better than some much more highly soluble salts. Gastric acid is not necessary for absorption of even poorly soluble preparations, so long as they are taken with meals. Because typical patients exhibit a wide range of absorption efficiencies, it is desirable to assess absorption fraction before beginning a supplement regimen. (Some patients will need three times as large a dose as others to absorb the same amount of calcium.) Calcium intakes up to at least 62.5 mmol (2500 mg) are safe for virtually all patients.