In Western countries, a shift to a diet rich in proteins from diverse sources could aid the transition to more sustainable patterns of protein consumption and production, contributing to meet the future demand for protein from the growing population. The successful integration of alternative proteins into diets hinges, however, on consumer acceptance. Despite a plethora of acceptance studies on alternative proteins, comparative insights remain limited. To improve the fragmented understanding of the drivers and barriers of alternative protein acceptance, this study examines consumer willingness in Germany to buy food products containing proteins from three sources—algae, crickets and jellyfish—using the same methodological approach. The findings indicate that environmental consciousness strengthens the willingness to buy products based on all three protein sources while neophobia weakens it. In contrast, past meat consumption habits contribute positively to the acceptance of animal-origin alternative proteins, like crickets and jellyfish, but negatively to the acceptance of algae. The acceptance is also influenced by demographic factors. It is argued that strategies targeting these factors can enhance the acceptance of alternative protein sources such as algae, crickets and jellyfish. However, it is important to tailor the strategies to the determinants that influence the willingness to buy products from a particular protein source.
