title: Superior calcium absorption from calcium citrate than calcium carbonate using external forearm counting.
abstract: 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.
authors: Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas 75235.
authors: J A
authors: JA
authors: Harvey
authors: P
authors: P
authors: Kenny
authors: J
authors: J
authors: Poindexter
authors: C Y
authors: CY
authors: Pak
mesh_terms: D000042:Absorption; D000328:Adult; D000368:Aged; D002119:Calcium Carbonate / Q000493:pharmacokinetics*; D002951:Citrates / Q000493:pharmacokinetics*; D019343:Citric Acid; D005260:Female; D006801:Humans; D008593:Menopause / Q000378:metabolism; D008875:Middle Aged
chemical_list: D002951:Citrates; D019343:Citric Acid; D002119:Calcium Carbonate