Musculoskeletal and Medication Practice Test

Calcium citrate is favored because its absorption doesn’t depend on stomach acidity. As people age, stomach acid often declines, making it harder for some calcium salts to dissolve and be absorbed. Calcium citrate dissolves readily in the intestines even with lower gastric pH, so it tends to be absorbed more reliably in older adults and is gentler on the stomach.

Calcium carbonate, by contrast, needs stomach acid to dissolve well, and its absorption can drop when acid production is reduced or when taken on an empty stomach. Calcium phosphate and calcium gluconate are less commonly used for routine oral supplementation; calcium gluconate provides less elemental calcium per dose and is more often used intravenously, while calcium phosphate doesn’t offer a clear absorption advantage for typical supplementation.