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

The UN's Sustainable Development Goals (SDGs) emphasize a shift towards sustainable food consumption to reduce environmental impacts. Protein sources, due to their high environmental influence, are crucial in sustainable diets. Consumer perceptions play a pivotal role in this shift, yet research on specific dietary groups' perceptions of protein sources is limited. This study addresses this gap by comparing the perceived sustainability attributes of eight common protein sources (poultry, pork, cheese, milk, eggs, fish, almonds, tofu) between reduced animal-based dieters (RABs) and nondieters (NDs). The study's context is the growing interest in sustainable consumption and the need to balance reduced animal-based consumption with cultural acceptability and nutritional needs. Previous research has explored consumer preferences for food labeling schemes, particularly nutritional and ecological scores, but less attention has been paid to the specific perceptions of RABs. This study aims to analyze demographic traits and food consumption patterns in both groups, assess perceived sustainability attributes (health and environmental friendliness) of common protein sources, and evaluate the importance of sustainability attributes (product category, nutritional score, ecological score, and price) using choice-based conjoint analysis. The novelty lies in focusing on the perceptions of RABs, providing a more nuanced understanding of sustainability perceptions compared to previous studies.

Existing literature highlights the environmental benefits of shifting towards plant-based diets, while acknowledging the challenges of cultural acceptability and potential micronutrient deficiencies associated with extreme plant-based diets. The use of score systems, such as nutritional and ecological scores, to facilitate sustainable consumer choices has also been explored. Studies have examined the effectiveness of various food labeling schemes through choice experiments, investigating the importance of sustainability-related attributes in consumer decisions regarding specific food products like beef or meat substitutes. However, inconsistencies exist in the literature regarding the impact of ecological scores on consumer choices. Some studies show a positive effect of eco-labels in influencing sustainable food choices, while others demonstrate a negative impact, potentially due to the inherent negative associations of ecological scores with products having higher environmental footprints. The need for targeted communication strategies tailored to different consumer segments, particularly reduced animal-based dieters, has been emphasized.

A cross-sectional online survey was conducted from April 7th to May 9th, 2022, using snowball sampling and Facebook ads to recruit participants aged 18 and older. The sample (n=639) was reduced to 541 after excluding participants under 18 and those with diet restrictions due to illness. The sample was then divided into two groups: NDs (n=247) and RABs (n=294). The questionnaire included sections on demographic traits, perceived sustainability attributes (health and environmental friendliness of eight protein sources on a 5-point Likert scale), food consumption frequency, and a choice-based conjoint analysis. The conjoint analysis utilized a full factorial design (64 combinations), reduced to 16 choice sets through orthogonal arrays. Respondents chose the more sustainable protein source from paired choices, with a 'no choice' option included. A nutritional and ecological scoring system was developed based on data from the USDA Food and Nutrient Database for Dietary Studies (FNDDS), the Fondazione Barilla Double Pyramid Technical Paper, and Hungarian online grocery store prices. The algorithms used for calculating the nutritional and ecological scores are described in detail within the paper. Portion sizes were standardized by nutritionists. Data analysis included chi-square tests for demographic comparisons, Mann-Whitney tests for perceived sustainability attributes, and conditional fixed effects regression models for conjoint analysis using the R programming environment.

Significant demographic differences were observed between NDs and RABs, with RABs showing a higher proportion of women, younger individuals, and those responsible for household food purchases. Food consumption frequency differed significantly across all eight protein sources, with RABs significantly less likely to consume animal-based proteins compared to NDs. Perceived healthiness differed significantly between groups for all protein sources. NDs rated all protein sources higher than RABs, especially animal-based sources. Conversely, RABs rated all sources except almonds lower on environmental friendliness than NDs. Conjoint analysis revealed a significant positive effect of nutritional scores on product sustainability for both groups, while the presence of ecological scores negatively impacted choices. Plant-based protein sources (almonds and tofu) had the greatest positive effect on choice for both groups. Importantly, all animal-based protein sources had a significant negative effect on the choices of RABs, indicating a strong preference against animal-based options within this group. Price did not significantly affect choices for either group.

The findings highlight significant differences in sustainability perceptions between RABs and NDs. NDs generally overestimated the healthiness of animal-based protein and underestimated the environmental impact of all sources. RABs showed a strong bias towards plant-based proteins and tended to underestimate the health benefits of animal-based sources. The positive effect of nutritional scores and the negative effect of ecological scores suggest that consumers prioritize nutritional quality but are negatively influenced by explicit environmental impact information. This points to the importance of understanding consumers' interpretations of different types of sustainability information. The strong negative effect of animal-based protein sources on RABs' choices warrants further investigation into the messaging used to promote sustainable protein sources within this dietary group. The study's limitations include the non-representative sample (overrepresentation of highly educated women) and the use of a self-reported dietary classification.

This study reveals significant differences in the perceived sustainability of protein sources between RABs and NDs, emphasizing the need for tailored communication strategies. Nutritional scores positively influence sustainability perceptions, while ecological scores have a negative impact. A strong preference for plant-based protein sources exists in both groups, but particularly among RABs. Future research should focus on developing targeted communication strategies to address misconceptions regarding the environmental and health aspects of both plant- and animal-based foods and explore the effectiveness of different types of sustainability labeling to better guide sustainable dietary choices. The development of national food-based dietary guidelines should also consider these differences in perception.

The study's sample was not fully representative of the general population, being biased toward highly educated women, potentially affecting the generalizability of the findings. Self-reported dietary information might not accurately reflect actual consumption patterns. The specific scoring system used could also influence the results, warranting further research with other scoring systems to verify the findings. Lastly, the reliance on online surveys might limit the generalizability to populations with limited internet access.