Nutrients are a critical driver of ecological interactions (e.g., plant-herbivore, predator-prey and host-parasite) but are not yet integrated into ecological networks. Ecological concepts like nutrient-specific foraging and nutrient-dependent functional responses provide invaluable mechanistic context to complex ecological interactions. These concepts in turn offer an opportunity to predict dynamic network processes such as interaction rewiring and cascading extinction events. Here, we propose the concept of nutritional networks. By integrating nutritional data into ecological networks, we envisage significant advances to our understanding of ecological dynamics at every scale from individuals to ecosystems. We summarise the potential influence of nutrients on the structure and complexity of ecological networks, with specific reference to niche partitioning, predator-prey dynamics, spatiotemporal patterns and robustness. Using an empirical example of an inter-specific trophic network, we show that networks can be constructed with nutritional data to disentangle the drivers of ecological interactions in natural systems. Throughout, we identify fundamental ecological hypotheses that can be explored in a nutritional network context, and highlight methodological frameworks to facilitate their operationalisation.