The human body absorbs calcium citrate supplements the easiest, followed by calcium phosphate and calcium carbonate, according to the Arthritis Foundation. The body absorbs all types of calcium supplements more efficiently when taken in smaller doses.
Calcium citrate is equally effective when taken with or without food, explains Mayo Clinic. Calcium citrate supplements are best for individuals with low stomach acid, absorption disorders or inflammatory bowel disease; however, calcium citrate supplements are also more expensive and contain less elemental calcium than calcium phosphate and calcium carbonate supplements. It is important to measure daily calcium intake prior to beginning a supplement regiment, as excessive calcium is potentially harmful.