Britannica Sources used in this answer

Why is precipitated calcium carbonate used in antacids and dietary supplements?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

A labeled diagram of the periodic table entry for calcium, showing its atomic number 20, symbol Ca, atomic weight 40.078, electron configuration, and classification as an alkaline-earth metal. Icons indicate calcium is a solid with a face-centered cubic crystal structure and strongly basic oxides at room temperature. — calcium The chemical element calcium is the most abundant metallic element in the human body.

Precipitated calcium carbonate is a synthetic form of calcium carbonate used in antacids and dietary supplements specifically because it provides a high level of purity.1

In its role as an antacid, calcium carbonate acts as a base that reacts with stomach acid (hydrochloric acid) to neutralize it, producing calcium chloride, carbon dioxide, and water. The use of the synthetic, precipitated form ensures that the product meets the stringent quality and purity standards required for medicinal and nutritional applications.21