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

• Published in: The American journal of clinical nutrition Vol. 79; no. 6; pp. 1053 - 1059
• Main Authors: Hambidge, K.M, Huffer, J.W, Raboy, V, Grunwald, G.K, Westcott, J.L, Sian, L, Miller, L.V, Dorsch, J.A, Krebs, N.F
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Clinical Nutrition 01.06.2004
• Subjects: absorption; administration & dosage; Adult; adults; bioavailability; Biological and medical sciences; Biological Availability; breeding; corn; Diet; Feeding. Feeding behavior; Female; Fundamental and applied biological sciences. Psychology; genes; genetics; Humans; hybrids; Intestinal Absorption; Male; minerals; mutants; nonlinear models; pharmacokinetics; pharmacology; phytic acid; Phytic Acid - administration & dosage; Phytic Acid - pharmacology; seeds; stable isotopes; tortillas; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Zea mays; Zea mays - genetics; zinc; Zinc - administration & dosage; Zinc - pharmacokinetics; Zinc Isotopes; Zinc Isotopes - pharmacokinetics; Human; Absorption; zinc absorption; Low; tortillas; Ratio; Maize; phytate:zinc molar ratio; Zinc; low-phytate maize hybrids
• ISSN: 0002-9165; 1938-3207
• 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 equal to 60% and approximately equal to 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.