title: Effect of phytic acid, tannic acid and pectin on fasting iron bioavailability both in the presence and absence of calcium.
abstract: OBJECTIVE
  To determine the effect of phytic acid, tannic acid and pectin on fasting non-heme iron bioavailability in both the presence and absence of calcium.
  
  
  METHODS
  Twenty-eight apparently healthy adult females participated in two iron absorption studies using radioactive iron isotopes ((59)Fe and (55)Fe). One group received 5mg of iron (as FeSO4) alone (control), together with 10mg of phytic acid, 100mg of tannic acid and 250mg of pectin (study A), on different days. The second group received the same iron doses and compounds as the other group, plus 800mg of calcium (CaCl2) (study B). The compounds were administered after an overnight fast, and no food or beverages were consumed for the following 3h. Iron status and circulating radioactivity were measured in venous blood samples.
  
  
  RESULTS
  The geometric means of iron bioavailability (range±1SD) for iron alone, iron with phytic acid, iron with tannic acid, and iron with citrus pectin were 25.0% (11.9-52.0); 18.9% (9.9-35.8); 16.8% (8.7-32.3); and 21.1% (10.2-43.9), respectively (repeated-measures ANOVA, p<0.02 (Dunnett's post hoc: control vs tannic acid p<0.05). When 800mg of calcium was added (study B), iron bioavailability was 16.7% (10.1-27.5); 13.2% (7.1-24.6); 14.8% (8.8-25.1); and 12.6% (5.5-28.8), respectively (repeated-measures ANOVA, NS).
  
  
  CONCLUSIONS
  Tannic acid decreases the fasting bioavailability of non-heme iron, however this effect did not exist in the presence of calcium. No effect was observed by phytic acid or citrus pectin on fasting non-heme iron bioavailability in both the presence and absence of calcium.
authors.affiliation: Micronutrient Laboratory, Institute of Nutrition and Food Technology, University of Chile, Santiago, Chile.
authors.forename: Ángela
authors.initials: Á
authors.lastname: Jaramillo
authors.affiliation: Micronutrient Laboratory, Institute of Nutrition and Food Technology, University of Chile, Santiago, Chile.
authors.forename: Lautaro
authors.initials: L
authors.lastname: Briones
authors.affiliation: Micronutrient Laboratory, Institute of Nutrition and Food Technology, University of Chile, Santiago, Chile.
authors.forename: Mónica
authors.initials: M
authors.lastname: Andrews
authors.affiliation: Micronutrient Laboratory, Institute of Nutrition and Food Technology, University of Chile, Santiago, Chile.
authors.forename: Miguel
authors.initials: M
authors.lastname: Arredondo
authors.affiliation: Micronutrient Laboratory, Institute of Nutrition and Food Technology, University of Chile, Santiago, Chile.
authors.forename: Manuel
authors.initials: M
authors.lastname: Olivares
authors.affiliation: Micronutrient Laboratory, Institute of Nutrition and Food Technology, University of Chile, Santiago, Chile; United States Department of Agriculture, Western Human Nutrition Research Center, University of California, Davis, USA.
authors.forename: Alex
authors.initials: A
authors.lastname: Brito
authors.affiliation: Micronutrient Laboratory, Institute of Nutrition and Food Technology, University of Chile, Santiago, Chile. Electronic address: fpizarro@inta.uchile.cl.
authors.forename: Fernando
authors.initials: F
authors.lastname: Pizarro
mesh_terms: D000328:Adult; D001682:Biological Availability; D002118:Calcium / Q000494:pharmacology*; D005215:Fasting / Q000378:metabolism*; D005260:Female; D006418:Heme / Q000378:metabolism; D006801:Humans; D007501:Iron / Q000378:metabolism*; D010368:Pectins / Q000494:pharmacology*; D010833:Phytic Acid / Q000494:pharmacology*; D013634:Tannins / Q000494:pharmacology*
chemical_list: D013634:Tannins; D006418:Heme; D010833:Phytic Acid; D010368:Pectins; D007501:Iron; D002118:Calcium
keywords: Calcium; Iron bioavailability; Pectin; Phytic acid; Tannic acid