The Difference Between Citracal & Caltrate

The mineral calcium is essential for the proper development, function and health of your bones and teeth, your nervous and circulatory systems and your muscles. You can get all the calcium your body needs from dairy products, vegetables and fortified drinks, but some people choose to take calcium supplements. Citracal and Caltrate are brand-name calcium supplements you can take to meet your daily calcium needs. Consult with your physician about the best form of calcium to take for your medical condition.

Caltrate contains calcium carbonate, a chemical found naturally in egg shells, snail and oyster shells, pearls, chalk, limestone and marble. Calcium carbonate is a relatively inexpensive and dense source of elemental calcium that contains 40 percent calcium by weight. One Caltrate 600 tablet provides 600 mg of calcium or 1,500 mg of calcium carbonate. The manufacturer of Caltrate also sells Caltrate chewable tablets and other tablets containing vitamin D and essential minerals.

Calcium carbonate does not dissolve very well in water. Under normal conditions, no more than 14 mg of calcium carbonate can dissolve in a liter of water. However, stomach acid helps your body absorb more calcium carbonate from Caltrate. As the Caltrate dose travels from the stomach to the intestines, about 36 percent of it makes it into your bloodstream. An analysis of past studies of calcium supplement absorption published in the "American Journal of Therapeutics," however, found that calcium carbonate was not as well absorbed as calcium citrate.

Caltrate can cause constipation, intestinal gas and bloating. In addition, it can interact with certain prescription medications. If you are taking drugs to block stomach acid or other prescription medications, consult with your physician about the best form of calcium to take.

Citracal does not contain a naturally occurring form of calcium like that found in Caltrate. Instead, it contains calcium citrate, which is made by mixing citric acid with calcium hydroxide. Citracal is less calcium-dense than Caltrate. Calcium citrate contains 21 percent calcium by weight. Two Citracal Regular tablets contain about 2,380 mg of calcium citrate, which yields 500 mg of elemental calcium. Citracal Regular also contains 400 IU of vitamin D to help your body use calcium more efficiently.

Citracal dissolves slightly better in water than Caltrate, and your body can absorb 20 percent more calcium from Citracal than from the same amount of Caltrate. A review of calcium supplements published in "Nutrition in Clinical Practice," however, found that some studies showed no difference in overall absorption levels from the two calcium supplements.

Unlike Caltrate, Citracal is not dependent upon the presence of stomach acid for absorption, so it can be taken with or without food. Finally, while Citracal causes fewer intestinal side effects than Caltrate, it does have the same potential for drug interactions.