Prebiotics in sport and exercise: current evidence, practical applications, and methodological considerations.

BACKGROUND: Prebiotics are selectively utilized by the host microbiota and can confer health and/or performance benefits, in part through increasing the abundance of beneficial gut microorganisms and their metabolites. While several studies have shown promising initial findings, high-quality scientific evidence examining the effects of prebiotics on athlete performance, health and wellbeing remains limited. METHODS: This narrative review summarizes the current available evidence on prebiotic intake in athletic populations, including effects on gastrointestinal structure and function, immune responses, recovery, sleep, wellness, mood and exercise performance. In areas where there is limited evidence in athletic cohorts, but a physiological rationale for a benefit, findings from sedentary and/or clinical populations are evaluated, and the potential relevance of these findings to athletes are discussed. Finally, considerations for practitioners around the use of prebiotics with athletes are provided, and recommendations for designing future prebiotic-based research are explored. RESULTS: Despite the limited existing literature around prebiotic use in athletes, there are several studies that indicate their potential to improve gut barrier integrity and reduce the incidence/severity of gastrointestinal symptoms. Data also indicates that prebiotics can increase salivary Immunoglobulin A secretion rate and reduce the duration and/or severity of upper respiratory symptoms in trained individuals. Other areas with emerging evidence that warrant further investigation in athletic populations include prebiotics' ability to support exercise adaptation and recovery, promote sleep improvements and enhance mood and cognitive function. The interpretation of current studies is limited by the lack of gut microbiome and metabolome measures and the absence of robust performance measures following a period of prebiotic supplementation. Well-controlled, adequately powered studies incorporating these outcomes are needed to determine the contexts in which prebiotic intake can meaningfully improve health and performance metrics, and to elucidate the underlying physiological mechanisms of any beneficial effects. CONCLUSION: Prebiotic intake represents a promising intervention to attenuate exercise-induced disturbances to the intestinal epithelium, reduce exercise-associated gastrointestinal symptoms, and lower the duration/severity of upper respiratory symptoms in athletes. Future studies should prioritize high-quality performance assessments, alongside comprehensive microbiome and metabolome profiling, to elucidate mechanistic effects. Areas with limited current evidence such as recovery, sleep, mood, cognitive function, bone health and nutrient absorption in athlete cohorts should also be further explored.