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Calcium Citrate Supplements Are Better Absorbed
What the Study Showed
In this small but well-designed 1999 study published in the Journal of Clinical Pharmacology, University of Texas researchers found that supplements containing calcium citrate were two and half times better absorbed than supplements made primarily of calcium carbonate.

How It Was Done
Eighteen postmenopausal women between the ages of 45 and 80 completed this three-phase investigation. For one week prior to each phase, the women restricted the amount of calcium and sodium they consumed through foods.

On the test day of each phase, the women ate a standard breakfast of farina with sugar, an egg, bread, and decaffeinated coffee; they took their calcium supplement with the meal.

In phase one, the subjects ingested 500 mg calcium citrate; phase two 500 mg calcium carbonate; and phase 3, a placebo. Blood was taken and checked for calcium levels before they took the supplement and every hour over the next eight hours.

Why It's Important
Calcium supplements are widely used, especially by postmenopausal women to help prevent the bone-thinning disease, osteoporosis. This admittedly small study indicated that commerical preparations made from calcium citrate were much better absorbed than commercial preparations of calcium carbonate.

The calcium citrate also produced a higher peak calcium level in the blood. This is an interesting finding because the carbonate supplements actually contain more calcium per pill than those with the citrate.

In fact, calcium carbonate products are probably the most popular calcium supplements. And it's well known that calcium carbonate is better absorbed when taken with a meal. Yet, in this study, the calcium carbonate supplements--even when taken with food--were still not as well absorbed as the calcium citrate.

Author: Howard J. Heller, Alan Stewart, Sharon Haynes, and Charles Y.C. Pak
Date Published: 02/14/2000
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