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Rural households in Africa face ‘postcode lottery’ on the nutritional content of their diets

New study reveals where potential interventions to address hunger and malnutrition could be targeted

Caption:Colleagues from the Amhara Region Bureau of Agriculture hand-threshing teff, a small-grained staple cereal crop, in a farmer’s field in Amhara region, Ethiopia. Credit: Martin Broadley

The amount of nutrients people receive from the crops that they eat is a type of ‘postcode lottery’, according to new analysis of thousands of cereal grains and soils in Malawi and Ethiopia published in Nature.

The global research team was led by the University of Nottingham, and included the London School of Hygiene & Tropical Medicine, Addis Ababa University (AAU) in Ethiopia and Lilongwe University of Agriculture and Natural Resources (LUANAR) in Malawi.

Working in GeoNutrition, a project to tackle hidden hunger, the researchers have discovered more about the relation between soils, crops and micronutrient deficiencies among people living in the two countries.

Dietary micronutrients calcium, iron, selenium, and zinc in the cereal grain varied substantially with location, with some areas showing much lower levels of micronutrients than others. Maps of the grain mineral concentrations are presented in the paper. These spatial effects are likely to be driven by soil type and other landscape-scale factors such as altitude and rainfall.

Diversifying diets may be important for improving nutrition, and the study found some cereal types, such as millets, are more nutritious than others, such as maize. However, this research shows that location is intrinsically linked to the nutritional quality of diets. This will particularly affect rural households who consume locally sourced food, including many smallholder farming communities where location may even be the largest influencing factor in determining the dietary intake of micronutrients.

Co-lead of the GeoNutrition project and co-author of the study Dr Edward Joy said: “Alleviating micronutrient deficiencies is essential for achieving Sustainable Development Goal 2, to end hunger and all forms of malnutrition by 2030.

“Our findings can help to identify where micronutrient deficiencies are most likely to occur at subnational scales in Ethiopia and Malawi, and where potential interventions such as supplementation, food fortification and crop biofortification could be targeted.”

Micronutrients include the vitamins and minerals which the body requires from the diet in small quantities, for a range of functions. Micronutrient deficiencies, also known as hidden hunger, are common globally, affecting more than half of children younger than five years of age, especially where access to sufficient food from plant and animal sources that are rich in micronutrients is limited for socioeconomic reasons.

These deficiencies pose a serious risk to human health, including the growth and cognitive development of children and susceptibility to infectious and non-communicable diseases.

Co-lead author Dr Dawd Gashu from Addis Ababa University said: “Nutritional surveillance work on the quality of staple cereals is an important part of wider public health policies to address micronutrient deficiencies. We hope that this type of work is now adopted in more countries.”

Co-lead author Dr Patson Nalivata from Lilongwe University of Agriculture and Natural Resources said: “By learning more about how the nutritional quality of cereal grains is linked to soil types and landscapes, as we have in this study, we are now better able to advise farmers how to choose and cultivate more nutritious crops.”

Martin Broadley, Professor of Plant Nutrition at the University of Nottingham and lead of the GeoNutrition project said: “It is important to have good quality evidence on the nutritional quality of diets if we are going to support public health and agriculture policies to improve peoples’ health and wellbeing. Mapping the quality of diets is an important part of this evidence.”

Other partners in this project include agricultural scientists, nutritionists, statisticians, ethicists and economists from Rothamsted Research and British Geological Survey in the UK. International partners include College of Medicine (University of Malawi), International Maize and Wheat Improvement Centre, International Crops Research Institute for the Semi-Arid Tropics and the World Agroforestry Centre

The project was funded primarily by the Bill & Melinda Gates Foundation and was supported by projects funded by the UK Government via the UKRI’s Global Challenges Research Fund the Royal Society, the Foreign, Commonwealth and Development Office and the Biotechnology and Biological Sciences Research Council.

Publication

D. Gashu, P. C.Nalivata, T. Amede, E. L. Ander, E. H. Bailey, L. Botoman, C. Chagumaira, S. Gameda, S. M. Haefele, K. Hailu, E. J. M. Joy, A. A. Kalimbira, D. B. Kumssa, R. M. Lark, I. S. Ligowe, S. P. McGrath, A. E. Milne, A. W. Mossa, M. Munthali, E. K. Towett, M. G. Walsh, L. Wilson, S. D. Young & M. R. Broadley. The nutritional quality of cereals varies geospatially in Ethiopia and Malawi. Nature. DOI:10.1038/s41586-021-03559-3.

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