Preparations in chewable or dissolvable tablets and liquids are easily absorbed, as they do not need to be broken down. These products are good for patients who have low acidity in their stomach. The most expensive are not necessarily the best. Therefore, it requires acid to be absorbed. Generally if calcium carbonate is taken with a meal the amount of acid increases in the stomach, which will help with absorption.
Calcium citrate is more soluble than calcium carbonate.
It does not require acid to be easily absorbed. Calcium lactate and gluconate are also soluble but provide less elemental calcium per tablet. Calcium dolomite, bone meal, and oyster-shell are not recommended as they may be contaminated with lead. The calcium absorption in the small intestine is lower from calcium carbonate than from calcium citrate, lactate or gluconate. Vitamin D Vitamin D increases calcium absorption and is important in the maturation of bone.