Results. The mean fractional absorption of zinc from zinc oxide (24.2 +/- 10.3%) was not significantly different than from zinc sulfate (23.2 +/- 10.5%).Background. Zinc deficiency is prevalent in developing countries. A strategy of zinc fortification of food is an appropriate method for large-scale interventions.Methods. Fifteen healthy adults were randomized to consume a tortilla fortified with 1.3 mg of elemental zinc (67Zn) from either zinc oxide or zinc sulfate after having received an intravenous dose of 70Zn. Two weeks later, subjects were crossed-over to receive the alternate zinc compound. Urine was collected 48 hours after each dose and analyzed for % enrichment of 67Zn and 70Zn by inductively coupled plasma mass spectrometry.Conclusion. Zinc oxide may be the preferred compound for fortification due to its greater chemical stability and lower cost.Objective. We compared the bioavailability of two zinc compounds using stable isotope methodology.