The effect of calcium carbonate and calcium citrate on the absorption of zinc in healthy female subjects.
OBJECTIVE
The aim of this study was to determine the effect of calcium carbonate and calcium citrate on zinc absorption.


METHODS
The zinc tolerance test (ZTT), which is the plasma zinc response to an oral zinc challenge, was used to quantitate zinc absorption. A physiological test dose of zinc (4.5 mg elemental zinc as 20 mg zinc sulphate) was used. Subjects underwent ZTTs on three separate occasions, each time consuming in random order, either 4.5 mg elemental zinc, zinc with 600 mg elemental calcium as calcium carbonate or zinc with 600 mg elemental calcium as calcium citrate.


METHODS
Metabolic ward conditions.


METHODS
Nine, free-living, healthy female subjects recruited from the University population.


METHODS
Blood samples were obtained at 30 min intervals for 4 h postdose.


RESULTS
The area under the plasma zinc curve (AUC) (mean +/- SEM) following the coingestion of zinc with calcium carbonate (438.4 +/- 129.0 mumol Zn.min/100 g albumin) and calcium citrate (308.0 +/- 110.5) was significantly lower (P < 0.017) than when zinc was ingested alone (1561.7 +/- 240). Urinary excretion of calcium was significantly higher (P < 0.017) at 4 h after supplementation with calcium citrate (0.83 +/- 0.12 mumol Ca/mumol creatinine) compared with calcium carbonate (0.40 +/- 0.11).


CONCLUSIONS
The decrease in zinc absorption following the ingestion of zinc with different forms of calcium suggests that an antagonistic competition occurred between the minerals and that elemental calcium is the inhibiting factor.
Argiratos
V
V
Department of Biochemistry, University of Sydney, NSW, Australia.
Samman
S
S
D000284:Administration, Oral; D000328:Adult; D000704:Analysis of Variance; D000863:Antacids / Q000494:pharmacology*; D002119:Calcium Carbonate / Q000378:metabolism / Q000494:pharmacology*; D002951:Citrates / Q000378:metabolism / Q000494:pharmacology*; D019343:Citric Acid; D004347:Drug Interactions; D005260:Female; D006801:Humans; D007408:Intestinal Absorption / Q000187:drug effects; D015032:Zinc / Q000097:blood / Q000493:pharmacokinetics*
D000863:Antacids; D002951:Citrates; D019343:Citric Acid; D002119:Calcium Carbonate; D015032:Zinc