Journal of the American College of Nutrition, Vol 13, Issue 6 575-577, Copyright © 1994 by American College of Nutrition

CLINICAL TRIAL

Effect of added citrate or malate on calcium absorption from calcium-fortified orange juice

C. Y. Pak, A. Stewart and S. D. Haynes
Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas 75235.

OBJECTIVE: Calcium absorption was determined from calcium-fortified diluted orange juice, which contained additional citrate or malate, in 16 normal subjects. METHODS: Each load of fortified orange juice with additional citrate (OJ+C) contained 300 mg Ca, 5.7 mEq malate, and 33.6 mEq citrate (10.4 mEq of which were added). Each load of orange juice with additional malate (OJ+M) had 300 mg Ca, 23.2 mEq citrate and 16.1 mEq malate (10.4 mEq of which were added). For each subject, fractional (intestinal) calcium absorption was measured by taking the ratio of fractional forearm radioactivity following an oral administration of OJ+C or OJ+M (labeled with 47Ca) and the fractional forearm radioactivity obtained after intravenous administration of trace 47Ca chloride on a separate occasion. RESULTS: There was no significant difference in fractional calcium absorption from the two calcium-fortified orange juice preparations (40.1 +/- 8.3% for OJ+C and 40.6 +/- 8.6% for OJ+M, p = 0.81). CONCLUSION: Calcium-fortified orange juice with additional citrate provides equivalent bioavailable calcium as the juice with additional malate.