Calcium

Also known as calcium carbonate, calcium citrate, electrolytes.

Last reviewed October 9, 2026 · Jump to references

What is Calcium?

In plain words

Calcium is a mineral that helps build bones and teeth. The body absorbs it through the gut, stores most of it in the skeleton, and uses small amounts to help muscles, nerves, and blood clotting work. Researchers study calcium for bone health and its role in preventing fractures. More is not always better: excess calcium can cause harm, including kidney stones in some people.

Technical definition

Calcium is an essential mineral and alkaline-earth element that occurs in the body primarily as calcium phosphate in bone and teeth and as Ca²⁺ ions in body fluids; calcium carbonate and calcium citrate are common supplemental salts. Ca²⁺ activates the calcium-sensing receptor and binds proteins such as calmodulin, supporting mineral balance, intracellular signaling, muscle contraction, nerve transmission, and blood clotting. In the United States, calcium products are marketed as dietary supplements, and some formulations are regulated as drugs for indications such as antacid use.

Educational information only. This page does not provide medical advice or determine whether a supplement is appropriate for you. Review supplements with a qualified healthcare professional, especially if you take medication, are pregnant, have surgery scheduled, or have a chronic medical condition.

Evidence by use

Each use is rated on its own. There is no single overall effectiveness score.