This calcium absorbs reliably and rarely upsets the stomach. It supplies elemental calcium to help maintain bone density, normal nerve transmission, and muscle contraction. Taking it with a meal improves absorption and lessens any digestive upset.
Space calcium from certain antibiotics (tetracyclines, fluoroquinolones) and thyroid drugs by at least 2 to 4 hours. Too much calcium, especially with high-dose vitamin D, can lead to hypercalcemia. People with kidney disease or sarcoidosis should talk to a doctor before use.