What is Elemental Calcium?

Elemental Calcium is an often confusing phrase and has been the subject of many calls we have received over the years. What does the word elemental mean as it relates to calcium, anyway? Allow us to take an opportunity to clear up any confusion:

Calcium is an element like iron, oxygen, or hydrogen. It cannot be broken down into any other forms. That is where the word elemental comes from. Elements easily join together to form compounds, otherwise known as molecules. Calcium combines with carbon and oxygen, two other elements, to make the very common dietary calcium formulation known as calcium carbonate, which is the main ingredient in TUMS. So, the molecule known as calcium carbonate contains elemental calcium, elemental carbon, and elemental oxygen.

When calcium carbonate is digested, the calcium that is bound to carbon and oxygen breaks away to return to its elemental form. This quantity is known as elemental calcium. The percentage of elemental calcium in calcium carbonate that is available for our bodies to absorb, is 40 %. It is this number of milligrams (mg) of elemental calcium that we need to count towards meeting our daily recommended amount of calcium. Using calcium carbonate as an example, for every tab that contains 1000 mg of calcium carbonate, 400 mg (the 40 %) of that tablet is elemental calcium and becomes available for absorption in the digestive system. In case you were wondering what the other 60 % of the tablet is, remember that it is the other two elements, carbon and oxygen.

Other calcium supplements work the same way. They are all calcium compounds which contain different amounts of elemental calcium, depending on the particular formulation. Another common calcium supplement formulation, calcium citrate, works the same way. It provides 20 % of the elemental calcium. This means that, if we take a 1000 mg tab of calcium citrate, we will have available 200 mg of calcium by itself.

So, it’s important to read the labels on any supplement that you take. Ask your pharmacist if it doesn’t seem clear. And remember, it’s the elemental calcium that counts!


Adapted from the Calcium Information Center.