title: Zinc absorption from low-phytate hybrids of maize and their wild-type isohybrids.
abstract: BACKGROUND
  Identification of allelic variants in a single gene that determine the phytate content of maize kernels and the subsequent breeding of low-phytate maize have facilitated studies designed to determine quantitatively the effects of maize phytate on the bioavailability of minerals in maize.
  
  
  OBJECTIVE
  The objective was to determine the relation between the fractional absorption of zinc (FAZ) and the phytate content and phytate:zinc molar ratios of maize tortillas prepared from hybrids with different phytate contents.
  
  
  METHODS
  Six healthy adults were fed, as the only food for 2 d, maize tortillas prepared from 1 of 2 low-phytate mutants: lpa1-1 (lpa1-1-LP) or Nutridense Low Phytate (ND-LP), which have phytate reductions of approximately 60% and approximately 80%, respectively, compared with their respective wild-type isohybrids. Four additional subjects were fed tortillas prepared from the corresponding wild-type isohybrids (lpa1-1-WT and ND-WT) according to the same study design. Meals were extrinsically labeled with zinc stable isotopes, and FAZ was determined with a dual-isotope-tracer ratio technique. Overall FAZ values were examined in relation to dietary phytate and phytate:zinc molar ratios by using a mixed nonlinear regression model.
  
  
  RESULTS
  The mean (+/-SD) FAZ values from tortillas prepared from ND-LP, lpa1-1-LP, lpa1-1-WT, and ND-WT were 0.38 +/- 0.07, 0.28 +/- 0.04, 0.15 +/- 0.07, and 0.13 +/- 0.05, respectively. A negative relation (P < 0.001) was found between FAZ and both dietary phytate and the phytate:zinc molar ratio. The effect of dietary zinc (8-14 mg Zn/d) under these experimental conditions was not significant.
  
  
  CONCLUSIONS
  FAZ from maize tortillas is positively related to the extent of phytate reduction achieved with low-phytate hybrids.
authors.affiliation: University of Colorado Health Sciences Center, Department of Pediatrics, Section of Nutrition, Denver 80262, USA. michael.hambidge@uchsc.edu
authors.forename: K Michael
authors.initials: KM
authors.lastname: Hambidge
authors.forename: John W
authors.initials: JW
authors.lastname: Huffer
authors.forename: Victor
authors.initials: V
authors.lastname: Raboy
authors.forename: Gary K
authors.initials: GK
authors.lastname: Grunwald
authors.forename: Jamie L
authors.initials: JL
authors.lastname: Westcott
authors.forename: Lei
authors.initials: L
authors.lastname: Sian
authors.forename: Leland V
authors.initials: LV
authors.lastname: Miller
authors.forename: John A
authors.initials: JA
authors.lastname: Dorsch
authors.forename: Nancy F
authors.initials: NF
authors.lastname: Krebs
mesh_terms: D000328:Adult; D001682:Biological Availability; D004032:Diet; D005260:Female; D006801:Humans; D007408:Intestinal Absorption; D008297:Male; D010833:Phytic Acid / Q000008:administration & dosage / Q000494:pharmacology*; D003313:Zea mays / Q000235:genetics*; D015032:Zinc / Q000008:administration & dosage / Q000493:pharmacokinetics*; D015033:Zinc Isotopes / Q000493:pharmacokinetics
chemical_list: D015033:Zinc Isotopes; D010833:Phytic Acid; D015032:Zinc