title: Zinc Absorption by Adults Is Similar from Intrinsically Labeled Zinc-Biofortified Rice and from Rice Fortified with Labeled Zinc Sulfate.
abstract: BACKGROUND
  Biofortification of staple food crops is a promising strategy to combat zinc deficiency, and it is of particular interest for rice and crops that are not consumed as flours and therefore not suitable for postharvest fortification. Because zinc absorption is decreased by phytic acid (PA) and perhaps other dietary components, it is important to measure the absorption of zinc from a biofortified crop before determining its efficacy.
  
  
  OBJECTIVE
  In this study, we compared the zinc absorption from zinc-biofortified rice (hydroponically enriched with (70)Zn) with that from a control rice of the same variety fortified with (70)ZnSO4 at point of use to reach the same total zinc content of 1.1 mg/meal. Both rice meals had a PA:Zn molar ratio of 12.
  
  
  METHODS
  Fractional absorption of zinc (FAZ) was measured with the use of the double-isotope tracer ratio method in 16 apparently healthy adults [18-45 y old; BMI (in kg/m(2)) 19-25] who consumed 2 single meals at 4-wk intervals in random order in a crossover design.
  
  
  RESULTS
  The FAZ from the biofortified rice (mean ± SD: 25.1 ± 8.7%) did not differ significantly from that of the point-of-use fortified rice (mean ± SD: 20.8 ± 7.1%) (P = 0.08).
  
  
  CONCLUSIONS
  These results suggest that the native zinc accumulated in the biofortified rice was readily released from the rice matrix and that its absorption by adults was influenced by PA and other food components in a similar way to the inorganic zinc compound added to the rice at point of use. Moreover, rice biofortification is likely to be as good as postharvest zinc fortification as an intervention strategy to combat zinc deficiency. This trial was registered at clinicaltrials.gov as NCT01633450.
authors.affiliation: Laboratory of Human Nutrition, Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland;
authors.forename: Marica
authors.initials: M
authors.lastname: Brnić
authors.affiliation: Laboratory of Human Nutrition, Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland;
authors.forename: Rita
authors.initials: R
authors.lastname: Wegmüller
authors.affiliation: Division of Human Nutrition and alida.melse@wur.nl.
authors.forename: Alida
authors.initials: A
authors.lastname: Melse-Boonstra
authors.affiliation: Centre for Crop Systems Analysis, Wageningen University, Wageningen, Netherlands; and.
authors.forename: TjeerdJan
authors.initials: T
authors.lastname: Stomph
authors.affiliation: Laboratory of Human Nutrition, Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland;
authors.forename: Christophe
authors.initials: C
authors.lastname: Zeder
authors.affiliation: Clinical Trials Center, University and University Hospital Zurich, Zurich, Switzerland.
authors.forename: Fabian M
authors.initials: FM
authors.lastname: Tay
authors.affiliation: Laboratory of Human Nutrition, Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland;
authors.forename: Richard F
authors.initials: RF
authors.lastname: Hurrell
mesh_terms: D000293:Adolescent; D000328:Adult; D001682:Biological Availability; D015992:Body Mass Index; D002523:Edible Grain / Q000737:chemistry; D005260:Female; D005527:Food, Fortified; D006801:Humans; D008297:Male; D008875:Middle Aged; D012275:Oryza / Q000737:chemistry; D010833:Phytic Acid; D055815:Young Adult; D015032:Zinc / Q000008:administration & dosage / Q000172:deficiency / Q000493:pharmacokinetics*; D019287:Zinc Sulfate / Q000008:administration & dosage / Q000493:pharmacokinetics*
chemical_list: D019287:Zinc Sulfate; D010833:Phytic Acid; D015032:Zinc
keywords: biofortified; fortified; intrinsic labeling; rice; zinc absorption