Addressing malnutrition with biofortified maize in Zimbabwe: from crop management to policy and consumers The double burden of malnutrition refers to the suboptimal intake of essential nutrients (minerals, metals and vitamins), either caused simply by inadequate dietary intake and/or due to the intake of "empty calories" i.e., food that has sufficient calories but lacks adequate amounts of essential nutrients. This double burden falls disproportionally heavy on developing countries, and there on women and children. It directly increases child mortality and childhood stunting, and reduces people's ability mending diseases. In Zimbabwe, an estimated one in four children have vitamin A deficiency, two-thirds are living with iron deficiency and one in three have iron deficiency anaemia (UNICEF, 2019). And a quarter of children (0.76 million) under five in Zimbabwe are currently stunted. Among women of reproductive age, one in four have vitamin A deficiency, six in ten women have iron deficiency and one in four are anaemic.   Malnutrition and its negative effects are particularly common in rural areas where people mostly live from their own crop production and the diet is mostly cereal based. This group is difficult to reach with supplements and has basically no access to fortified processed food. As an alternative method, plant breeders developed "biofortified" crops, meaning crops with a higher content of minerals, metals and (pro)vitamin A (PVA). However, recent research has shown that the effectiveness of such biofortified crops is a) affected considerably by soil characteristics, and that b) their nutrient content can be enhanced with micronutrient fertilizer and other crop management options. To enable making best use of the new biofortified crop varieties we propose the following research:  Work package (WP) 1: what are the effects of agronomic management options on PVA concentration and micronutrient uptake of novel, biofortified maize lines. African soils are often poor and have a low fertility, resulting in low yields and low grain quality. This can, for example, be addressed with soil conservation methods (increased return of crop residues and reduced tillage), with macro and micro nutrient treatments, or with liming. However, little is known how such treatments affect the nutrient content in the newly developed biofortified maize varieties. We will, therefore, test a range of the new varieties under several agronomic management options, to identify the best conditions and treatments for high quality, nutritious maize.   WP2. Testing the effectiveness of agronomic biofortification at the farm-scale. As mentioned above, African soils are often poor, but they are also very variable. Farmers of course know their soils well, they know where the crops grow well and where not, and they often increase soil fertility in particular fields (where they dump kitchen refuse or crop residues, where the cattle are kept at night, etc). Therefore, farmers could grow biofortified crops in preferential places but it is unknown how much this could contribute to an improved nutritional value. We will test these options with 60 farmers for two seasons for their effectiveness, feasibility, and possible impact.   WP3. Closing the nutrient gap or Predicting the effect of bio + agro fortification at the national level. Although maize is a very important staple for most people in Zimbabwe, they also eat other food. And only their total "food basket" determines their nutrient uptake. Knowledge of the food basket composition and of the nutrient content of all items in the basket allows then to estimate the possible contribution of the bio-and agro-fortified food on the nutrition of the people. WP3 will estimate this impact for all regions in Zimbabwe based on WP1 and WP2 results in combination with national statistics on food consumption and, where necessary, some additional analysis of common food items.   WP4. This WP focuses on upscaling and dissemination and has no research components. The Global Challenges Research Fund (GCRF) supports cutting-edge research to address challenges faced by developing countries. The fund addresses the UN sustainable development goals. It aims to maximise the impact of research and innovation to improve lives and opportunity in the developing world. The fund addresses the UN sustainable development goals. It aims to maximise the impact of research and innovation to improve lives and opportunity in the developing world.