Zinc absorption from low-phytate hybrids of maize and their wild-type isohybrids

Am J Clin Nutr. 2004 Jun;79(6):1053-9. doi: 10.1093/ajcn/79.6.1053.


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.

Design: 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.

Publication types

  • Clinical Trial
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Biological Availability
  • Diet*
  • Female
  • Humans
  • Intestinal Absorption
  • Male
  • Phytic Acid / administration & dosage
  • Phytic Acid / pharmacology*
  • Zea mays / genetics*
  • Zinc / administration & dosage
  • Zinc / pharmacokinetics*
  • Zinc Isotopes / pharmacokinetics


  • Zinc Isotopes
  • Phytic Acid
  • Zinc