The impact of probiotic supplementation on mucosal immunity and oxidative stress after high-intensity exercise among athletes: a meta-analysis

Abstract Objective Athletes engaging in strenuous exercise can experience a heightened risk for upper respiratory symptoms and immune disorders triggered by exercise. This meta-analysis examined the relationship between probiotic supplementation, exercise, mucosal immunity, and oxidative stress (OS) levels following high-intensity exercise. Methods We systematically searched four electronic databases to identify eligible studies for subsequent screening. The inclusion criteria are as follows: (1) Adults athletes; (2) Randomised Controlled Trial (RCT); (3) The experimental group received probiotic supplementation (Exp), while the control group received placebo (Con) supplementation; (4) Pre- and post-high-intensity exercise assessments of OS markers and salivary immunoglobulin A (sIgA) were conducted. Use the Cochrane bias risk assessment tool to evaluate the quality of the selected study. Select Standardized Mean Difference (SMD) as the appropriate effect scale index, and use Revman 5.4 software to analyze the mean difference of the selected article data. Results A total of eight studies fulfilled the inclusion criteria and were selected for the meta-analysis. The results showed that the Exp group showed a significantly greater reduction in OS levels after high-intensity exercise compared to the Con group (SMD, -0.38 [-0.76, -0.01], p < 0.05, I 2 = 0%). In addition, the Exp group showed a significantly greater improvement in sIgA levels compared to the Con group (SMD, 0.55 [0.09, 1.02], p < 0.05, I 2 = 0%). Subgroup analysis showed that EXP group with more than 6 weeks significantly improved sIgA level (SMD, 0.78 [0.16, 1.41], p < 0.05, I 2 = 0%), but not less than 6 weeks (SMD, 0.26 [-0.44, 0.96], p = 0.47, I 2 = 0%). Conclusion Probiotic supplementation, especially for more than 6 weeks, may enhance antioxidant capacity and mucosal immunity following high-intensity exercise.