Carbohydrate Mouthwashes Enhance Exercise and Cognitive Performance under Fed Conditions: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background Carbohydrate (CHO) mouthwash improves performance by stimulating oral receptors linked to brain regions involved in motor control and motivation, without requiring digestive processing. Most research has focused on fasting states, but the effects of postprandial CHO mouthwash remain inconclusive. Objectives This study aims to synthesize existing studies on the impact of postprandial CHO mouthwash on exercise and cognitive performance, offering insights for future research and practical recommendations for athletes and coaches. Methods Six databases (Pubmed, Web of Science, Cochrane Library, Embase, SciELO and SPORTDiscus) were systematically searched for articles up to February 2025 and screened using EndNote 21th. Statistical analysis was conducted using metafor package in Rstudio (2024.09.1), and results were visualized with ggplot2 package. Results Thirty-five articles met inclusion criteria, with two studies on cognitive performance included in the systematic review and thirty-three on exercise performance included in both the systematic review and meta-analysis. Overall, CHO mouthwash was found to improve cognitive performance under fed conditions compared to placebo and meta-analysis further supported the enhancement of exercise performance (Hedges' g = 0.18, 95% CI [0.09, 0.28], p < 0.01). Moderator and meta-regression analysis revealed that CHO mouthwash appeared to be more effective in improving exercise performance under fed conditions when aerobic exercise was performed, maltodextrin mouthwash was used, mouthwash duration was ≤ 10 s, and a high-CHO meal was consumed before exercise (p < 0.05). Conclusion This systematic and meta-analytic review supports the view that CHO mouthwash can still improve exercise and cognitive performance under fed conditions.