Critical evaluation of strategies for mineral fortification of staple food crops

Staple food crops, in particular cereal grains, are poor sources of key mineral nutrients. As a result, the world's poorest people, generally those subsisting on a monotonous cereal diet, are also those most vulnerable to mineral deficiency diseases. Various strategies have been proposed to deal with micronutrient deficiencies including the provision of mineral supplements, the fortification of processed food, the biofortification of crop plants at source with mineral-rich fertilizers and the implementation of breeding programs and genetic engineering approaches to generate mineral-rich varieties of staple crops. This review provides a critical comparison of the strategies that have been developed to address deficiencies in five key mineral nutrients-iodine, iron, zinc, calcium and selenium-and discusses the most recent advances in genetic engineering to increase mineral levels and bioavailability in our most important staple food crops.