Acute inhibition of iron bioavailability by zinc: studies in humans
- 672 Downloads
Iron (Fe) and zinc (Zn) deficiencies constitute two of the most important nutritional and public health problems affecting developing countries. Combined supplementation or fortification with Zn and Fe are strategies that can be used to improve the Zn and Fe status of a population. However, there is concern about potential negative interactions between these two micronutrients due to a competitive binding to DMT1 and Zip14 transporter. Studies performed in humans have shown an inhibitory effect of Zn on Fe absorption when both minerals are given together as a solution in fasting conditions. We found that at low doses of iron (0.5 mg) the threshold for the inhibition of iron bioavailability was at a Zn:Fe wt/wt ratio ≥5.9:1, whereas at higher doses of Fe (10 mg) this inhibition occurred at 1:1 Zn:Fe wt/wt ratio. This differential response could be explained by the variation in the abundance of both cations as they compete for a limited number of shared transporters at the enterocyte. Conflicting results have been obtained when this interaction was studied in different food matrices. A negative interaction was not observed when Fe and Zn were provided in a composite hamburger meal, premature formula, human milk, or cow milk. A decrease on Fe absorption was observed in only 1 of 3 studies when Fe and Zn were supplied in wheat flour. The possibility of a negative interaction should be considered for supplementation or fortification programs with both microminerals.
KeywordsIron absorption Zinc Iron Interactions DMT1 Humans
Supported by grants from the National Fund for Scientific & Technological Development (FONDECYT) 1100094, 1070665, and 1040879.
- Abd Rashed A (2011) In vitro study to determine the effect of zinc on non-heme iron absorption. IJCRIMPH 3:354–368Google Scholar
- Bolívar L, Olivares M, López de Romaña D, Pizarro F (2011) Efecto del zinc sobre la absorción de hierro de leche de vaca fortificada con hierro, zinc y ácido ascórbico (Effect of zinc on iron absorption from cow’s milk fortified with iron, zinc and ascorbic acid). Rev Chil Nutr 38 (Suppl 1):1135 (Abstract)Google Scholar
- Espinoza A, Le Blanc S, Olivares M, Pizarro F, Ruz M, Arredondo M (2011) Iron, copper, and zinc transport: inhibition of divalent metal transporter 1 (DMT1) and human copper transporter 1 (hCTR1) by shRNA. Biol Trace Elem Res Nov 9. [Epub ahead of print]Google Scholar
- International Zinc Nutrition Consultative Group (IZiNCG) (2004) Technical document #1. Assessment of the risk of zinc deficiency in populations and options for its control. Food Nutr Bull 25 (suppl 2):S94–204Google Scholar
- López de Romaña D, Salazar M, Hambidge KM, Penny ME, Peerson JM, Sian L, Krebs NF, Brown KH (2005). Iron absorption by Peruvian children consuming wheat products fortified with iron only or iron and one of two levels of zinc. Proceedings of FASEB Experimental Biology, San Diego, 2–6 April 2005 (Abstract 274.23)Google Scholar
- McLean E, Egli I, Cogswell M, de Benoist B, Wojdyla D (2007) Worldwide prevalence of anemia in preschool aged children, pregnant women and non-pregnant women of reproductive age. In: Kraemer KZM (ed) Nutritional anemia. Sight and Life Press, Switzerland, pp 1–12Google Scholar
- Olivares M, Wiedeman A, Pizarro F, López de Romaña D (2010) Efecto de dosis crecientes de zinc sobre la absorción de hierro de una leche fortificada con hierro (Effect of increasing doses of zinc on iron absorption from an iron-fortified milk). Rev Chil Pediatr 81:592 (Abstract)Google Scholar
- Schultink W, Merzenich M, Gross R, Shrimpton R, Dillon D (1997) Effects of iron-zinc supplementation on the iron, zinc, and vitamin A status of anaemic pre-school children. Food Nutr Bull 18:311–316Google Scholar