Journal of the American College of Nutrition, Vol 9, Issue 6 583-587, Copyright © 1990 by American College of Nutrition

JOURNAL ARTICLE

Superior calcium absorption from calcium citrate than calcium carbonate using external forearm counting

J. A. Harvey, P. Kenny, J. Poindexter and C. Y. Pak
Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas 75235.

Calcium absorption from calcium citrate was compared with that obtained from calcium carbonate in 20 normal women. It was measured by external forearm counting technique, where the ratio of forearm radioactivity after an oral dose of labeled calcium salt (containing 500 mg calcium) and after an intravenous injection of trace radiocalcium represented fractional calcium absorption. The fractional calcium absorption from calcium citrate was 39.2 +/- 8.6%, which was significantly higher than the 31.2 +/- 9.4% derived from calcium carbonate (p less than 0.001). Seventeen subjects displayed greater calcium absorption from calcium citrate. The remaining three patients, with a lower calcium absorption from the citrate salt, had high levels of calcium absorption from calcium carbonate. It is concluded that calcium is better absorbed from calcium citrate than calcium carbonate when these salts are taken on an empty stomach in most women. The exception might be those with optimum calcium absorption from calcium carbonate.