title: Bioavailability of zinc oxide added to corn tortilla is similar to that of zinc sulfate and is not affected by simultaneous addition of iron.
abstract: BACKGROUND
  Corn tortilla is the staple food of Mexico and its fortification with zinc, iron, and other micronutrients is intended to reduce micronutrient deficiencies. However, no studies have been performed to determine the relative amount of zinc absorbed from the fortified product and whether zinc absorption is affected by the simultaneous addition of iron.
  
  
  OBJECTIVE
  To compare zinc absorption from corn tortilla fortified with zinc oxide versus zinc sulfate and to determine the effect of simultaneous addition of two doses of iron on zinc bioavailability.
  
  
  METHODS
  A randomized, double-blind, crossover design was carried out in two phases. In the first phase, 10 adult women received corn tortillas with either 20 mg/kg of zinc oxide added, 20 mg/kg of zinc sulfate added, or no zinc added. In the second phase, 10 adult women received corn tortilla with 20 mg/kg of zinc oxide added and either with no iron added or with iron added at one of two different levels. Zinc absorption was measured by the stable isotope method.
  
  
  RESULTS
  The mean (+/- SEM) fractional zinc absorption from unfortified tortilla, tortilla fortified with zinc oxide, and tortilla fortified with zinc sulfate did not differ among treatments: 0.35 +/- 0.07, 0.36 +/- 0.05, and 0.37 +/- 0.07, respectively. The three treatment groups with 0, 30, and 60 mg/kg of added iron had similar fractional zinc absorption (0.32 +/- 0.04, 0.33 +/- 0.02, and 0.32 +/- 0.05, respectively) and similar amounts of zinc absorbed (4.8 +/- 0.7, 4.5 +/- 0.3, and 4.8 +/- 0.7 mg/day, respectively).
  
  
  CONCLUSIONS
  Since zinc oxide is more stable and less expensive and was absorbed equally as well as zinc sulfate, we suggest its use for corn tortilla fortification. Simultaneous addition of zinc and iron to corn tortilla does not modify zinc bioavailability at iron doses of 30 and 60 mg/kg of corn flour.
authors: Universidad Autónoma de Querétaro, Querétaro, México. jlrosado@prodigy.net.mx
authors: Jorge L
authors: JL
authors: Rosado
authors: Margarita
authors: M
authors: Díaz
authors: Elsa
authors: E
authors: Muñoz
authors: Jamie L
authors: JL
authors: Westcott
authors: Karla E
authors: KE
authors: González
authors: Nancy F
authors: NF
authors: Krebs
authors: María C
authors: MC
authors: Caamaño
authors: Michael
authors: M
authors: Hambidge
mesh_terms: D000042:Absorption; D000328:Adult; D001682:Biological Availability; D015992:Body Mass Index; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D005433:Flour; D005527:Food, Fortified; D006801:Humans; D019266:Iron, Dietary / Q000008:administration & dosage* / Q000097:blood; D016014:Linear Models; D018977:Micronutrients / Q000008:administration & dosage; D055815:Young Adult; D003313:Zea mays; D015032:Zinc / Q000008:administration & dosage / Q000097:blood; D015034:Zinc Oxide / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics*; D019287:Zinc Sulfate / Q000008:administration & dosage
chemical_list: D019266:Iron, Dietary; D018977:Micronutrients; D019287:Zinc Sulfate; D015032:Zinc; D015034:Zinc Oxide