Ann. N.Y. Acad. Sci. ISSN 0077-8923 ANNALS OF THE NEW YORK ACADEMY OF SCIENCES Issue: Technical Considerations for Maize Flour and Corn Meal Fortification in Public Health Bioavailability of iron, zinc, folic acid, and vitamin A from fortified maize Diego Moretti, 1 Ralf Biebinger, 2 Maaike J. Bruins, 3 Birgit Hoeft, 4 and Klaus Kraemer 5 1 Laboratory of Human Nutrition, Department of Health Sciences and Technology, Institute of Food Nutrition and Health, ETH Z¨ urich, Z ¨ urich, Switzerland. 2 Rheinland-Pfalz, Germany. 3 DSM Food Specialties, Delft, the Netherlands. 4 DSM Nutritional Products Ltd., Basel, Switzerland. 5 Sight and Life, Basel, Switzerland Address for correspondence: Dr. Diego Moretti, ETH Z¨ urich, Department of Health Sciences and Technology, Institute of Food Nutrition and Health, Laboratory of Human Nutrition, Schmelzbergstrasse 7, 8092 Z ¨ urich, Switzerland. diego.moretti@hest.ethz.ch Several strategies appear suitable to improve iron and zinc bioavailability from fortified maize, and fortification per se will increase the intake of bioavailable iron and zinc. Corn masa flour or whole maize should be fortified with sodium iron ethylenediaminetetraacetate (NaFeEDTA), ferrous fumarate, or ferrous sulfate, and degermed corn flour should be fortified with ferrous sulfate or ferrous fumarate. The choice of zinc fortificant appears to have a limited impact on zinc bioavailability. Phytic acid is a major inhibitor of both iron and zinc absorption. Degermination at the mill will reduce phytic acid content, and degermed maize appears to be a suitable vehicle for iron and zinc fortification. Enzymatic phytate degradation may be a suitable home-based technique to enhance the bioavailability of iron and zinc from fortified maize. Bioavailability experiments with low phytic acid–containing maize varieties have suggested an improved zinc bioavailability compared to wild-type counterparts. The bioavailability of folic acid from maize porridge was reported to be slightly higher than from baked wheat bread. The bioavailability of vitamin A provided as encapsulated retinyl esters is generally high and is typically not strongly influenced by the food matrix, but has not been fully investigated in maize. Keywords: maize; bioavailability; iron; zinc; phytic acid Introduction Effective fortification programs aim to improve the bioavailable nutrient intake of the whole popula- tion, with the intent of eliminating or preventing micronutrient deficiencies in the general popula- tion and the most vulnerable groups. Being widely consumed, maize flour is a suitable vehicle for mass fortification. 1 It serves as a major staple food in several African and Latin American countries 2 and may be fortified with one or more micronutrients, such iron, zinc, folic acid, and/or vitamin A. As for other mass fortification programs, fortification of centrally processed maize flour on a large scale may not reach population groups not having access to processed foods. Bioavailability refers to the amount of ingested micronutrient absorbed and utilized in the body and can be influenced by the chemical form of the forti- ficant, the nutrient composition of the fortification premix, the dietary composition and food matrix, the overall dietary intake, and the physiological state of target individuals. A fortification program there- fore needs to be adjusted to the consumption pattern and composition of the staple food in question, as well as the regional diet and individual factors in the target population. This article reviews the prop- erties of added fortificants to maize flour and the dietary and individual factors affecting the nutrient bioavailability of added iron, zinc, folic acid, and vitamin A. Maize flour fortification Major maize-consuming countries are located in Central America and Sub-Saharan Africa, and Egypt is also a major maize-consuming country. Large- scale produced maize flour is degermed and sold as flour or grits, and can be precooked. 3 In several countries, maize flour is usually consumed as gruel or porridge, and in certain settings, a fermentation, doi: 10.1111/nyas.12297 54 Ann. N.Y. Acad. Sci. 1312 (2014) 54–65 C  2013 New York Academy of Sciences.