The increased use of legumes is viewed as a promising option to mitigate climate change, as they are a source of proteins and provide nitrogen to the soil. In this paper, we evaluate a strategy for the increased use of legumes in Europe until 2050 by integrating a large array of food and natural system processes into a consistent modeling framework. Three contrasting scenarios are studied: a supply-side scenario entailing a change in the animal feed mix, a demand-side scenario entailing a shift in human diet, and a combination of the shift in human diet with a reforestation in Europe. We find that mitigated emissions are much higher in the two diet shift scenarios (-231 and -259 MtCO2eq, respectively) than in the supply-side scenario (-10 MtCO2eq). Therefore, the main environmental benefit of legumes is to provide proteins as a substitute for animal products rather than enabling a lower consumption of synthetic fertilizer through increased leguminous nitrogen fixation. Diet shift scenarios require a lower use of lands that can then be used to either reduce intensification or reforest. In the former case, the reduction in emissions concerns almost exclusively non-CO2 emissions, mainly through enteric fermentation and manure management, and occurs largely outside Europe. In the latter case, the livestock sector still represents a substantial share of the emission reduction but is outpaced by CO2 emissions through carbon sequestration. An increase in legume production substantially reduces greenhouse gas emissions from the AFOLU sector only when combined with a change in diet, and its combination with reforestation allows the emission reduction to be relocated to Europe through carbon sequestration. Our study concludes that an increase in legume production accompanied by appropriate measures on both the supply and demand side can be effective in reducing emissions. These results can be used to design the European Commission's “Farm to Fork” strategy for sustainable foo