Food for thought: The underutilized potential of tropical tree-sourced foods for 21st century sustainable food systems

1. The global food system is causing large-scale environmental degradation and is a major contributor to climate change. Its low diversity and failure to produce enough fruits and vegetables is contributing to a global health crisis. 2. The extraordinary diversity of tropical tree species is increasingly recognized to be vital to planetary health and especially important for supporting climate change mitigation. However, they are poorly integrated into food systems. Tropical tree diversity offers the potential for sustainable production of many foods, providing livelihood benefits and multiple ecosystem services including improved human nutrition. 3. First, we present an overview of these environmental, nutritional and livelihood benefits and show that tree-sourced foods provide important contributions to critical fruit and micronutrient (vitamin A and C) intake in rural populations based on data from sites in seven countries. 4. Then, we discuss several risks and limitations that must be taken into account when scaling-up tropical tree-based food production, including the importance of production system diversity and risks associated with supply to the global markets. 5. We conclude by discussing several interventions addressing technical, financial, political and consumer behaviour barriers, with potential to increase the consumption and production of tropical tree-sourced foods, to catalyse a transition towards more sustainable global food systems.