Used as a stable isotopic tracer in medical and scientific research, particularly in breath tests to assess gastrointestinal conditions and gastric function. When ingested, the ¹³C-labeled calcium carbonate reacts with stomach acid to produce ¹³CO₂, which is measured in exhaled breath. This non-invasive method allows for accurate evaluation of gastric processes such as acid secretion and emptying. It is also employed in metabolic studies to track calcium absorption and bone turnover, and in environmental research to study carbon cycling without radioactive risk.