In general, a calcium supplement is recommended for individuals who do not meet their daily requirements through diet alone. Bone meal or dolomite should be avoided, as they may contain toxic ingredients. Calcium carbonate contains the highest amount of elemental calcium. When properly taken, it is well absorbed.
Calcium carbonate is probably the most cost-effective supplement.
It must be taken on a full stomach to be properly absorbed, since hydrochloric acid is excreted in response to eating, which enhances absorption. In some individuals, calcium carbonate may cause gas or constipation. In such cases, increased fluid intake and increased activity are recommended. If these measures are unsuccessful, then switching to another calcium formulation is recommended. The only disadvantages are the higher cost and the lower percent of elemental calcium.