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

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.