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Difference Between Calcium Citrate and Calcium Carbonate

Calcium Citrate vs Calcium Carbonate

Calcium is a micronutrient essential to bone development, heartbeat regulation, and muscular construction. It bears the atomic number 20 and is abundant at the Earth’s surface, both at land and sea. The element is essential for the daily nutrition of the body.

There are two important forms of calcium; calcium citrate and calcium carbonate. Both are calcium salts that can also be used as calcium supplements to prevent or treat calcium deficiencies. Calcium, which is positively charged, is paired with negatively charged elements like citrate and carbonate to form calcium citrate and calcium carbonate, respectively.

Calcium citrate and calcium carbonate are not the same. Here are where the differences lie:

Chemical Formula

Calcium citrate has the chemical formula Ca3(C6H5O7)2 while calcium carbonate has the  formula CaCO3. Both appear as solid in the form of a white powder.


Calcium citrate is more easily absorbed than calcium carbonate. This is because the acid in calcium citrate aids the absorption of the compound even without the need for water or any liquid for its absorption. Calcium carbonate, meanwhile, needs acidic food and drink for absorption to take place.

Calcium Content

The downside of calcium citrate is that a tablet contains only 21 percent calcium, while the calcium content in every pill of calcium carbonate is higher at 40 percent. Henceforth, a person needs to take more calcium citrate to get roughly the same amount of calcium found in calcium carbonate.


Calcium citrate appears in capsule form which makes them easier to swallow compared to the larger calcium carbonate pills.

Functions and Uses

Aside from being used as calcium supplements, calcium citrate and calcium carbonate are also used as food preservatives, additives, and flavor agents. But while calcium citrate is also used to soften “hard water,” calcium carbonate is the cause of “hard water.”

Calcium carbonate is also used as an antacid, relieving some conditions like heartburn. It is also used in the construction industry since it can form into quicklime when the compound is heated. The quicklime can be made into marble and limestone. On the other hand, calcium citrate leaves citric acid behind if the compound is separated from each other.

Side Effects

Both calcium compounds have side effects, usually as allergic reactions. Calcium citrate can cause headaches and constipation while calcium carbonate can produce gas and indigestion.


Calcium citrate is more expensive to purchase compared to calcium carbonate.


  1. Chemically, calcium carbonate and calcium citrate are not the same; they have different chemical formulas. Calcium citrate has the chemical formula Ca3(C6H5O7)2 while calcium carbonate has the formula CaCO3.
  2. Calcium carbonate and calcium citrate are two forms of calcium and used as calcium salts. These calcium compounds are used as supplements for people who have calcium deficiencies. In both cases, the positively charged calcium is paired with a negatively charged particles like citrate and carbonate.
  3. As calcium supplements, both calcium carbonate and calcium citrate differ in many respects. Calcium citrate, for instance, has a better absorption rate compared to calcium carbonate. Calcium citrate does not need any acidic food or drink when it is taken. However, calcium carbonate has a higher calcium content compared to calcium citrate. The latter supplement only has 21 percent calcium while calcium carbonate has a higher rate of 40 percent.
  4. Calcium carbonate is usually packaged in large pills, making them hard to swallow for some people. Meanwhile, calcium citrate comes in small capsules for easy intake and digestion.
  5. Due to its content and package size, a person who takes calcium citrate has to take more compared to a person taking calcium carbonate.
  6. The price between the two calcium supplements also differs. Calcium citrate is priced higher than calcium carbonate.

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  1. I was reading your article about calcium citrate being more easily absorbed than calcium carbonate. Is that still true if a person takes LIQUID calcium carbonate with Vitamin D? My doctor told me to take 1200 units per day (with vitamin D), but did not specify citrate or carbonate.

  2. Calcium citrate is always better than cal carbonate-
    1)Least chances of Renal calculi
    2) Cal Citrate can be taken with or with out food.. Whereas cal carbonate has to be taken with food orealse person will have Belching, Bloting and Burping.
    3)Cal citrate is more bio-available them cal Carbonate
    4)Cal carbonate effects Phosphate absorption which is one of the main component for bone health. Whereas cal citrate don’t

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