Athletes’ Readiness for Alternative Protein Sources and Green Eating Practices: Towards a More Sustainable Diet in Sports Nutrition

Background Dietary protein is vital for athletic performance, recovery, and long-term health; however, has a significant impact on the environment. Sustainable alternative proteins may fulfil athletes’ performance requirements while reducing ecological impact, yet their acceptance in the athletic population remains underexplored. This study aimed to assess professional athletes’ acceptance of alternative protein sources (plant-based, insect-derived, single-cell, and in vitro proteins) and to examine their association with green eating behaviors, providing insights for sustainable sports nutrition strategies. Methods A cross-sectional online survey was conducted (February–May 2023) among 223 professional athletes aged 15–45 years with ≥ 6 months of regular training. The questionnaire assessed sociodemographic and sport characteristics, dietary habits, Green Eating scale, and acceptance of alternative protein sources (plant-based, insect-based, single-cell, in vitro meat) on a five-point Likert scale. Ordinal logistic regression identified predictors of acceptance. Analyses were performed in SPSS v22 (p < 0.05). Results Among 223 professional athletes (59% male; mean age 19.9 ± 4.6 years), plant-based protein showed the highest acceptance (81%), while insect protein, single-cell protein, and in vitro meat were least accepted (22–27%). Male gender predicted lower acceptance of plant-based protein (OR = 0.223, p = 0.004). Lack of sustainable nutrition education, lower decisional balance pros scores, and higher home self-efficacy were significant negative predictors for single-cell protein and in vitro meat acceptance (all p < 0.020). Conclusion Professional athletes showed high acceptance of plant-based proteins but limited acceptance of insect-based, single-cell, and in vitro meat proteins. Sustainable nutrition education and positive decisional balance were key predictors of acceptance, highlighting the need for targeted educational strategies to promote environmentally sustainable protein choices in sports nutrition.