Differences in perspectives on sustainability attributes of dietary protein sources between reduced animal-based dieters and nondieters

The United Nations Sustainable Development Goals envision a sustainable future that includes a shift in food consumption, aiming to reduce anthropogenic environmental impacts. Protein sources are crucial in sustainable diets because of their high environmental influence. Although consumers play a pivotal role in driving the shift towards more sustainable food consumption patterns, research on the perceptions of specific dietary groups regarding protein sources is limited. In this study, the perceived sustainability attributes of eight common protein sources between reduced animal-based dieters (RABs) and nondieters (NDs) were evaluated. Using a cross-sectional survey, we measured demographic data, food consumption frequency, perceived healthiness, and environmental friendliness. We performed conjoint analysis on the importance of the protein sources’ sustainability attributes (nutritional score, ecological score, price, product category). In total, 294 RABs and 247 NDs participated. The majority of the sample consisted of highly educated, childless women aged 18–39 years with high incomes, residing in cities, and responsible for food in their households. The presence of a nutritional score had a positive effect on both consumer groups’ perceptions of product sustainability, whereas the presence of an ecological score negatively affected consumer preferences for more sustainable products. The perceptions of the sustainability of protein sources varied significantly between RABs and NDs. Overall, RABs underestimated the healthiness of animal-based products, whereas NDs underestimated the environmental impact of protein sources. Among the animal-based protein sources, eggs and fish were seen as the most sustainable, with significantly higher means for NDs (p < 0.001). Among the sustainability attributes, plant-based foods and nutritional scores had a significant positive effect on both groups’ choices. For RABs, all animal-based protein sources had a significant negative effect on food choice. These results support the assumption that nutritional scores can improve the nutritional quality of food choices, whereas ecological scores can reduce the environmental impact of food choices. These findings underscore the need for tailored communication strategies and interventions to promote sustainable food choices among diverse dietary groups.