review
Calcium Citrate vs Carbonate: Which Calcium Supplement Is Best?
Comparing the two most popular supplemental calcium forms: stomach acid requirements, elemental calcium percentage, and GI tolerability.
By Nourish By Nutrients Editorial Team •
Updated: October 2026
Key Evidence Takeaways:
- Calcium Carbonate contains 40% elemental calcium and requires stomach acid (take with meals).
- Calcium Citrate contains 21% elemental calcium and is absorbed with or without food.
- Citrate is preferred for older adults or those taking acid-reducing PPI medications.