Gelbiotic: Developing a fruit-based bioactive matrix to support the Gut-Muscle Axis in endurance athletes

Abstract Introduction. Exercise-induced gastrointestinal (GI) distress affects a substantial proportion of endurance athletes, yet conventional energy gels remain biochemically inert formulations unable to address its underlying mechanisms of splanchnic hypoperfusion, tight-junction degradation and reactive oxygen species accumulation. The "Gelbiotic" concept integrates a 40% whole-fruit matrix with a stabilized postbiotic fraction derived from Lacticaseibacillus fermentation to simultaneously deliver optimized carbohydrate oxidation and proactive intestinal barrier protection within a single formulation. Objective. To formulate a Gelbiotic prototype built around a 1:0.8 glucose-to-fructose ratio and evaluate its sensory attributes, functional ingestion parameters and drivers of palatability against a leading commercial isotonic gel (SiS Go Isotonic) using a blinded, randomized crossover protocol. Materials and Methods. A cohort of physically active participants was recruited from the University of Almería and evaluated three formulations across six counterbalanced sequences using a validated 9-point Likert scale. Sensory attributes assessed included Taste, Sweetness, Acidity, Texture, Swallowability and Stickymouth. Statistical analysis was performed applying paired t-tests, ANOVA and Pearson correlation with simple linear regression. Results. Biochemical analysis confirmed that the prototype met its target carbohydrate ratio and caloric density, with preserved antioxidant capacity following fermentation and pasteurization. Sensory evaluation revealed complete mechanical and structural parity with the commercial benchmark across all physical dimensions, while a significant deficit in overall Taste was identified, driven by suppressed Sweetness and elevated Acidity attributable to the compounded organic acid load of the fruit matrix and lactic acid fermentation. Perceived Sweetness emerged as the primary statistical driver of overall palatability for the prototype, and physical Texture was entirely independent of Swallowability, confirming robust pseudoplastic hydrogel behavior. High-volume endurance athletes showed preferential prototype adoption, suggesting a strong product-market fit for this population. Conclusions. The Gelbiotic prototype fulfills its core formulation and functional objectives, delivering a physiologically validated carbohydrate matrix enriched with a bioactive postbiotic and polyphenolic fraction targeting the primary mechanisms of exercise-induced mucosal barrier disruption. Its single identified limitation, a flavor-axis deficit rooted in sweetness suppression and excess acidity, is biochemically tractable and resolvable without modifying the validated hydrogel architecture. The Gelbiotic concept represents a scientifically coherent and practically viable functional sports supplement, successfully unifying high-flux carbohydrate delivery with proactive intestinal resilience.