Human micronutrient deficiencies: linkages with micronutrient deficiencies in soils, crops and animal nutrition.

Abstract

AbstractMicronutrient contents (trace elements and minerals) of foods are partially determined by the micronutrient content and availability of the soils on which the foods are grown. In principle, under conditions of soil micronutrient deficiency, micronutrient contents of food crops can be increased by the application of micronutrients as fertilizer. The first objective of this chapter is to analyse and document the occurrences and the strengths of the linkages between micronutrient deficiencies in soils, crops, animal and human nutrition. The second objective is to assess whether micronutrient application as fertilizer can be a realistic and feasible approach in addressing human micronutrient deficiencies. Literature in the fields of soil science, agriculture, ecology, animal nutrition and human nutrition has been searched in order to document and analyse, as completely as possible, the relationships between micronutrients in soils, food crops, animal and human nutrition. Evidence for direct quantitative relationships between micronutrient deficiency in soils and in human nutrition is most clearly available for iodine and selenium, and possibly also for zinc. For zinc and selenium, addition of these micronutrients to soils can substantially increase crop micronutrient content, and thus contribute to ameliorating human micronutrient deficiency. When considering various approaches in addressing human micronutrient deficiencies, such as dietary diversification, micronutrient supplementation, micronutrient fortification of foods, developing new varieties through plant breeding and genetic manipulation, there appears to be, for some micronutrients, sufficient evidence to consider micronutrient fertilization as an alternative approach, with its own specific advantages. Currently, the most promising candidate for this approach is zinc.