The importance of calcium for preventing osteoporosis is probably its most well-known role. Although calcium plays at least some minor role in lower blood pressure, the mechanisms involved appear complex and remain somewhat unclear. However, people with a history of kidney stones must talk with a doctor before supplementing calcium, because such supplementation might actually increase the risk of forming stones for the small number of people who absorb too much calcium. Calcium also appears to partially bind some fats and cholesterol in the gastrointestinal tract. Perhaps as a result, some older research suggests that calcium supplementation may help lower cholesterol levels.
Most dietary calcium comes from dairy.
Choosing a form of calcium supplement can be confusing. While fewer pills of the calcium carbonate form are needed, this form doesn't absorb as well as some other forms of calcium. CCM is increasingly the form of calcium recommended by nutritionally oriented doctors. Only preliminary research exists regarding the amino acid chelates of calcium, and conclusions cannot be drawn at this time. Severe deficiency of both calcium and vitamin D is called rickets in children and osteomalacia in adults.