Calcium after bariatric surgery

14 Nov 2023 | Bariatric Surgery, Evidence Based Medicine, Gastric Bypass

Calcium is the most abundant mineral in the human body, although almost all of it is stored in the bones and teeth.  Calcium is also used by the body for nerve conduction, blood clotting and other processes.  Calcium in our diet comes mainly from dairy products such as milk, cheese and yoghurt, but can also be found in tofu, almonds and broccoli.  Some plant milks are fortified with extra calcium.

Because most of the calcium in our body is stored in our bones, when we do not get enough in our diet, our body will ‘borrow’ this out of our bones.  Over the long term this can lead to weakening of the bones (osteoporosis) and an increased risk of fractures.

The American Society of Metabolic and Bariatric Surgery recommends that people get 1200-1500mg per day of elemental calcium in their diet from all sources.  People who have had a gastric bypass operation will usually need to take calcium supplements as their ability to absorb calcium is reduced, but calcium supplements may also be needed after sleeve gastrectomy.  

Calcium supplements are commonly available in one of two forms, calcium carbonate and calcium citrate.  Calcium carbonate is available on prescription but is not as well absorbed after gastric bypass operations, or when people are taking acid suppressing medications like pantoprazole.  Calcium carbonate also needs to be taken with meals, and can cause constipation or kidney stones.  Calcium citrate is not available on prescription but can be purchased on line including from  It is better absorbed, particularly after gastric bypass operations or when people are taking acid suppressing medications.  Calcium citrate also does not need to be taken with meals and has a lower chance of causing constipation or kidney stones as side effects compared with calcium carbonate.