Monday, 10 July 2006 - 4:20 PM

Does a Food Chain Approach Help to Target Zinc Bio-Fortification Efforts in Cereal Crops?.

Tjeerdjan Stomph, Maja A. Slingerland, Ellis Hoffland, and Rob Nout. Wageningen Univ, PO Box 430, Wageningen, Netherlands

Worldwide it has been estimated that 2 billion people suffer from iron and zinc deficiency-related health problems. For zinc the attained population is mainly situated in developing countries. A food chain approach is proposed to improve the density of bio-available zinc in the cereal crops sorghum and rice, being staple foods in West Africa and China respectively. This coherent integrated approach combines soil science, soil-plant interactions, crop physiology, post-harvest handling, food technology and human nutrition epidemiology. The ultimate challenge of the program is to improve human uptake of zinc by the poor from their mainly plant-derived foods. In Africa agronomic measures are proposed to enhance zinc and to keep phytic acid/zinc ratios moderate followed by processing to decrease phytic acid/zinc ratios further. Results from the program show that enhancement of zinc through improved soil management is possible as this goes together with improved productivity. The current trend in soil management recommendations, though, would rather lead to a decreased nutritional quality through lower bio-availability of zinc from cereals in the diet. The food chain approach has helped to highlight how a broader view is needed to avoid choices in soil management that will show counterproductive in the longer term. The food technology work has highlighted how the enhanced phytic acid accumulation in cereal seeds as a consequence of the need to fertilize with phosphorus can be coped with at later stages during the food chain. In China the possibilities to enhance zinc through agronomic measures currently seem too limited. Without genetic improvements the levels of zinc that seem attainable are insufficient. When rice production systems change from flooded to aerobic conditions the problem probably even becomes more acute. Reducing phytic acid/zinc ratios in order to improve zinc bio-availability could be attained both through improved agronomic measures. The need for this though is low as there are ample possibilities to counter the negative effect of phytic acid during processing. The comparison of the two productions chains show how answers are context specific. It also shows how the food chain approach.

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