<s>[INST] I read that if you are taking certain medications, you cannot absorb calcium supplements. Is this the case? [/INST] Proton pump inhibitors (PPIs) are a type of medicine that reduces stomach acids. They are usually prescribed because a patient’s stomach acid levels are too high, and the medication reduces the acids to a more normal level. You might consider calcium citrate rather than calcium carbonate if you are on these drugs because calcium citrate does not require stomach acid to break it down. 

Calcium carbonate may cause acid rebound where the stomach overcompensates for the high dose of calcium carbonate, which is alkaline, by churning out more acid. Source: American Bone Health. Link: https://americanbonehealth.org/frequently-asked-questions/. Field: Rheumatology. Disease: Ostoeporosis </s>