Biofortified Cereals Increase Dietary Zinc Intake: Wheat and Maize as Case Studies

Abstract

The World Health Organisation estimates that dietary zinc deficiency affects 31% of the global population, with rates as high as 73% in some low- and middle-income countries. Zinc biofortification of staple crops, such as maize in Guatemala and wheat in Pakistan has the potential to offer a sustainable, low-cost strategy to increase dietary zinc intake on a population scale. This chapter reviews the efficacy and effectiveness studies conducted with biofortified wheat and maize, exploring the strengths and weaknesses of this strategy alongside supplementation and food fortification. Biofortified cereals stand out, particularly due to their minimal behavior disruption, potential for sustainable scale-up and accessibility to vulnerable groups. Trials have demonstrated that consuming biofortified cereals can increase daily zinc intake by amounts ranging from 21% to 169% compared with consuming standard varieties. However, there is limited evidence regarding the translation of this increase into improved human health. Challenges stem from a high phytate intake, a major inhibitor of zinc absorption associated with plant-rich diets, and a lack of sensitive biomarkers to detect subtle changes in dietary zinc intake through biofortification. Mechanical methods such as micro-milling that aim to boost mineral bioavailability are being explored. Investigating novel biomarkers remains a priority for better monitoring of interventions to increase zinc intake. Functional indicators such as anthropometric data have generally failed to show measurable impacts from consuming biofortified foods, but there are some positive findings related to self-reported morbidities. Long-term interventions are recommended for tracking functional outcomes resulting from incremental zinc intakes through biofortification.