Differences between calcium carbonate and calcium citrate supplements include absorption, calcium content and pill size. Citral is a popular calcium citrate brand, while Caltrate and Tums are popular calcium carbonate brands.
One of the big differences between calcium carbonate and calcium citrate is how the body absorbs them. Calcium is best absorbed where acid is present. Calcium citrate does not require additional stomach acid to aid absorption, making it the best absorbed calcium supplement. This means that users can take the supplement on an empty stomach or at any time of day. People with stomach acid problems should avoid calcium citrate supplements.
Calcium carbonate is alkaline based, meaning the presence of additional stomach acid is required for smooth absorption. For this reason, users should take calcium carbonate supplements with orange juice or right after meals.
Calcium content is another significant difference between the two supplements. Calcium citrate is lower in elemental calcium, requiring users to take more pills per day compared to calcium carbonate. Calcium carbonate is the more popular option mainly because of the higher concentration of elemental calcium.
The two supplements differ in pill size. Calcium carbonate pills are usually bigger than calcium citrate options and may be more difficult to swallow for some people.