Diet & Fitness

Calcium is an element that typically occurs in nature in combination with other molecules. Calcium compounds that are used as nutritional supplements include:

• Calcium chloride
• Calcium carbonate
• Calcium bound to amino acids ("amino acid chelate")
• Hydroxyapatite (an extract of bone meal)

Most forms of calcium are absorbed to a similar degree, although calcium carbonate is poorly absorbed when taken on an empty stomach by a person who has little or no stomach acid. It is true that one study showed calcium citrate-malate is somewhat better absorbed than certain other forms. However, for practical purposes, the research has not demonstrated a clear advantage of any one form of calcium over the others.

Here are two considerations:

Bulk

Some calcium salts are bulkier than others. For example, calcium carbonate contains about 40% calcium, whereas calcium citrate contains only around 21% calcium. Consequently, to obtain the same number of milligrams of calcium, one would have to take more tablets or capsules of calcium citrate than of calcium carbonate.

Price

Calcium carbonate is generally less expensive than other forms of calcium.

Since calcium is a commodity and is not patented, companies will sometimes make claims that the form of calcium they sell is somehow superior. However, there is little, if any, data to support claims of superiority for calcium from amino acid chelates, microcrystalline hydroxyapatite, colloidal calcium, or coral calcium.