title: Phytic acid concentration influences iron bioavailability from biofortified beans in Rwandese women with low iron status.
abstract: BACKGROUND
  The common bean is a staple crop in many African and Latin American countries and is the focus of biofortification initiatives. Bean iron concentration has been doubled by selective plant breeding, but the additional iron is reported to be of low bioavailability, most likely due to high phytic acid (PA) concentrations.
  
  
  OBJECTIVE
  The present study evaluated the impact of PA on iron bioavailability from iron-biofortified beans.
  
  
  METHODS
  Iron absorption, based on erythrocyte incorporation of stable iron isotopes, was measured in 22 Rwandese women who consumed multiple, composite bean meals with potatoes or rice in a crossover design. Iron absorption from meals containing biofortified beans (8.8 mg Fe, 1320 mg PA/100 g) and control beans (5.4 mg Fe, 980 mg PA/100 g) was measured with beans containing either their native PA concentration or with beans that were ∼50% dephytinized or >95% dephytinized.
  
  
  RESULTS
  The iron concentration of the cooked composite meals with biofortified beans was 54% higher than in the same meals with control beans. With native PA concentrations, fractional iron absorption from the control bean meals was 9.2%, 30% higher than that from the biofortified bean meals (P < 0.001). The quantity of iron absorbed from the biofortified bean meals (406 μg) was 19% higher (P < 0.05) than that from the control bean meals. With ∼50% and >95% dephytinization, the quantity of iron absorbed from the biofortified bean meals increased to 599 and 746 μg, respectively, which was 37% (P < 0.005) and 51% (P < 0.0001) higher than from the control bean meals.
  
  
  CONCLUSIONS
  PA strongly decreases iron bioavailability from iron-biofortified beans, and a high PA concentration is an important impediment to the optimal effectiveness of bean iron biofortification. Plant breeders should focus on lowering the PA concentration of high-iron beans. This trial was registered at clinicaltrials.gov as NCT01521273.
authors.affiliation: Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland Groundwork LLC, Crans-près-Céligny, Switzerland nico@groundworkhealth.org.
authors.forename: Nicolai
authors.initials: N
authors.lastname: Petry
authors.affiliation: Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland ETH-Board, Science Section, Zurich, Switzerland.
authors.forename: Ines
authors.initials: I
authors.lastname: Egli
authors.affiliation: Department of Clinical Biology, School of Medicine, University of Rwanda, Butare, Rwanda; and.
authors.forename: Jean B
authors.initials: JB
authors.lastname: Gahutu
authors.affiliation: Department of Clinical Biology, School of Medicine, University of Rwanda, Butare, Rwanda; and.
authors.forename: Pierrot L
authors.initials: PL
authors.lastname: Tugirimana
authors.affiliation: International Food Policy Research Institute, Washington, DC.
authors.forename: Erick
authors.initials: E
authors.lastname: Boy
authors.affiliation: Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland.
authors.forename: Richard
authors.initials: R
authors.lastname: Hurrell
mesh_terms: D000293:Adolescent; D000328:Adult; D001682:Biological Availability; D018592:Cross-Over Studies; D007887:Fabaceae / Q000737:chemistry*; D005260:Female; D005504:Food Analysis; D005527:Food, Fortified; D006801:Humans; D007501:Iron / Q000097:blood* / Q000737:chemistry / Q000493:pharmacokinetics*; D010833:Phytic Acid / Q000737:chemistry*; D012432:Rwanda; D055815:Young Adult
chemical_list: D010833:Phytic Acid; D007501:Iron