title: Calcium does not inhibit the absorption of 5 milligrams of nonheme or heme iron at doses less than 800 milligrams in nonpregnant women.
abstract: Calcium is the only known component in the diet that may affect absorption of both nonheme and heme iron. However, the evidence for a calcium effect on iron absorption mainly comes from studies that did not isolate the effect of calcium from that of other dietary components, because it was detected in single-meal studies. Our objective was to establish potential effects of calcium on absorption of nonheme and heme iron and the dose response for this effect in the absence of a meal. Fifty-four healthy, nonpregnant women were selected to participate in 4 iron absorption studies using iron radioactive tracers. We evaluated the effects of calcium doses between 200 and 1500 mg on absorption of 5 mg nonheme iron (as ferrous sulfate). We also evaluated the effects of calcium doses between 200 and 800 mg on absorption of 5 mg heme iron [as concentrated RBC (CRBC)]. Calcium was administered as calcium chloride in all studies and minerals were ingested on an empty stomach. Calcium doses ≥1000 mg diminished nonheme iron absorption by an average of 49.6%. A calcium dose of 800 mg diminished absorption of 5 mg heme iron by 37.7%. In conclusion, we demonstrated an isolated effect of calcium (as chloride) on absorption of 5 mg of iron provided as nonheme (as sulfate) and heme (as CRBC) iron. This effect was observed at doses higher than previously reported from single-meal studies, starting at ~800 mg of calcium.
authors.affiliation: Micronutrients Laboratory, Nutrition and Food Technology Institute, University of Chile, Santiago, Chile. dgaitancharry@yahoo.com
authors.forename: Diego
authors.initials: D
authors.lastname: Gaitán
authors.forename: Sebastián
authors.initials: S
authors.lastname: Flores
authors.forename: Pía
authors.initials: P
authors.lastname: Saavedra
authors.forename: Constanza
authors.initials: C
authors.lastname: Miranda
authors.forename: Manuel
authors.initials: M
authors.lastname: Olivares
authors.forename: Miguel
authors.initials: M
authors.lastname: Arredondo
authors.forename: Daniel
authors.initials: D
authors.lastname: López de Romaña
authors.forename: Bo
authors.initials: B
authors.lastname: Lönnerdal
authors.forename: Fernando
authors.initials: F
authors.lastname: Pizarro
mesh_terms: D000328:Adult; D018798:Anemia, Iron-Deficiency / Q000188:drug therapy; D002118:Calcium / Q000008:administration & dosage / Q000494:pharmacology*; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005260:Female; D006418:Heme / Q000493:pharmacokinetics*; D006801:Humans; D007501:Iron / Q000008:administration & dosage* / Q000493:pharmacokinetics* / Q000627:therapeutic use; D008875:Middle Aged
chemical_list: D006418:Heme; D007501:Iron; D002118:Calcium