Quantitative and qualitative food losses of African indigenous vegetables along the value chain: A systematic literature review

African indigenous vegetables (AIV) have high densities of important micronutrients but qualitative and quantitative food losses along the value chains could threaten their nutritional potential in Africa. We conduct a systematic review of the estimations of food quality losses of AIV along their value chains. Our review reveals that there is generally limited evidence on food quality losses along AIV value chains. In addition, existing studies are often of low quality and have inadequate experimental descriptions. For our final analysis, we consider the yields and malnutrition-relevant nutrients for two major AIV, vegetable amaranth ( Amaranthus ssp ) and African nightshade ( Solanum nigrum and Solanum scarbrum ). We observe a consistent and substantial decrease in carotenoids and iron contents starting from selecting appropriate seed material to processing practices. Losses are particularly severe at seed selection and production. Almost half of the original potential is lost after cultivation for the reviewed nutrients. While qualitative losses appear to be significant during post-harvest, processing by consumers leads to comparatively small reductions. While our results suggest that the current value chains need to be improved to supply nutrient-rich foods to urban and peri-urban areas, better data are also needed to conduct more comprehensive assessments of nutrition-sensitive AIV value chains and to derive evidence-based interventions to reduce nutrient losses for AIV along the value chain.