Key messages:

• Leakage of reactive nitrogen (Nr) from food systems threatens the environment and human health by causing air, water and soil pollution, while contributing to climate change and biodiversity loss. Nitrogen use efficiency (NUE) of the EU food system was only 18% in 2015. Most of the remaining 82% was wasted by loss to the environment contributing to these environmental and health threats.
• A combination of dietary change and technical measures across the food chain can halve nitrogen waste (as the sum of all nitrogen losses) and contribute to reaching the targets set in UNEP’s Colombo Declaration, the EU Farm to Fork Strategy and the Kunming-Montreal Global Biodiversity Framework.
• A transition towards plant-based diets will reduce nitrogen inputs and increase the NUE of the food system, since plant-based foods have higher NUE than animal-based foods. Diets that are predominantly plant-based correlate with lower nitrogen footprints, lower greenhouse gas emissions and positive health outcomes compared with current diets in the EU.
• Among 144 scenarios investigated, a combination of halved meat and dairy consumption (demitarian) with improved farm and food chain management, and reduction of excess energy and protein intake achieves 49% reduction in nitrogen losses with the highest score for net societal benefit.
• Full exclusion of meat and dairy products from human diet combined with ambitious technical measures could reduce the need for virgin nitrogen inputs by 73% and achieve a food system NUE of close to 50%. Taking these factors together, such a change could reduce nitrogen waste by up to 84%. However, this scenario did not offer net societal benefit when the environmental benefits were offset against the stringency of actions needed.
• At farm level, there is scope for significant improvement in NUE using available technologies. Values of farm-level NUE of up to 92% for arable systems, 80% for granivores, 61% for ruminant meat production, and 55% for dairy production can be achieved. 
• Only about 55% of the nitrogen in commodities leaving the farm-gate suitable as human food is actually used for human consumption. This leaves considerable scope to improve the NUE of the whole food system by reducing food waste and improving wastewater treatment, with an emphasis on nutrient recovery opportunities.
• Agroecological approaches, urban and high-technology food production systems (e.g., vertical or indoor farms) may support a transition towards plant-based diets and sustainable food systems. Investing in legumes, novel and future foods offer opportunities for consumers to reduce the consumption of animal-based foods, with multiple environmental benefits.
• A range of policies addressing consumer food choices is available for public authorities to support dietary change towards lower nitrogen footprint diets. Policy makers are encouraged to combine policy instruments in coherent policy packages to reduce nitrogen inputs in the food system, increase NUEs and monitor their effectiveness, as well as possible adverse side-effects.
• Bottom-up approaches to sustainable food systems are increasingly emerging at local and regional level and require ambitious strategies to facilitate a transition towards a plant-based food system, including novel foods and new food production technologies.
• The unprecedented rise of energy, fertilizer and food prices since 2021 underlines the need to address the vulnerability of the food system. A transition towards plant-based diets requires less land and mineral fertilizers, thus reducing energy dependency and increasing resilience to food and energy crises.
• This report adds evidence on the need and actions to transform the food system based on a systems approach. Encouraging more plant-based diets can promote human health and a healthier planet.