UC Irvine

BACKGROUND: Plant-based diets are known to be beneficial for cardiovascular health and promote environmental sustainability. However, many athletes avoid plant-based diets due to concerns of protein inadequacy. OBJECTIVES: To investigate the impact of two predominately plant-based diets-whole food plant-based (WFPB) and plant-based meat alternatives (PBMA)-vs. an omnivorous diet, favoring red meat and poultry (Animal), on endurance and muscular strength. METHODS: 12 recreational runners and 12 resistance trainers were assigned to three diets-WFPB, PBMA, and Animal-for 4 weeks each, in random order. Primary outcomes for runners (12-minute timed run) and resistance trainers (composite machine strength) were collected at baseline and after diets, along with secondary performance outcomes and dietary data. RESULTS: 22 recreational athletes completed the study (age: 26.2 ± 4.4 years; sex: 10 female, 12 male; BMI: 23.1 ± 2.4 kg/m2). Mean differences in 12-minute timed run - WFPB vs. Animal (- 23.4 m; 95% CI: - 107 to 60.0 m) and PBMA vs. Animal (- 2.9 m; 95% CI: - 119 to 113 m) - were not significant. Mean percent differences in composite machine strength - WFPB vs. Animal (- 2.7%; 95% CI: - 5.8 to 0.4% and PBMA vs. Animal (- 0.7%; 95% CI: - 3.5 to 2.2%) - were not significant. Average protein intake for all diets met International Society for Sports Nutrition recommendations. CONCLUSIONS: Our findings suggest recreational athletes can maintain athletic performance on both an omnivorous diet and two diets that are predominately plant-based. TRIAL REGISTRATION: NCT05472701. Retrospectively registered.