Comparing the Effects of Glucose-Fructose versus Glucose on the Oxidation Rate: A Systematic Review and MetaAnalysis

Background: Numerous studies have aimed to compare the effects of glucose (Glu) consumption with those of glucose-fructose (Glu-Fru) consumption on oxidation rates during exercise. However, divergent outcomes have surfaced due to variations in exercise protocols and concurrent substance ingestion, leading to a lack of consensus. This systematic review and meta-analysis investigated the comparative effects of Glu and Glu-Fru on total carbohydrate oxidation, endogenous carbohydrate oxidation, exogenous carbohydrate oxidation, and total fat oxidation rates during exercise. Methods: A systematic search of PubMed, Scopus, and Web of Science databases up to February 2023. The search yielded 14 randomized controlled trials involving 125 endurance athletes. Results: The meta-analyses revealed that Glu supplementation significantly increased total carbohydrate oxidation (WMD: 0.21 g/min) compared to Glu-Fru. Endogenous carbohydrate oxidation significantly increased with Glu (WMD:-0.12), while Glu-Fru led to increased exogenous carbohydrate oxidation (WMD: 0.27 g/min). Total fat oxidation decreased with Glu-Fru (WMD:-0.06 g/min). Conclusion: By investigating athletic nutrition complexities, our findings shed light on metabolic responses to Glu-Fru versus Glu supplementation. Tailoring hydration strategies, athletes should select an optimal Glu-Fru to Glu ratio for maximal oxidation and enhanced performance. Future research could explore dose-response relationships for optimal metabolic benefits during exercise.