The Performance Gut: Microbiome Insights for Elite Athletes

What the review covers

Carlone, Parisi and Fasano (Frontiers in Sports and Active Living, October 2025) screened 117 papers across PubMed, Scopus and Web of Science and synthesised 19 studies on high-level athletes — 12 experimental trials and 7 systematic or narrative reviews. The goal: map how training load, sport type and nutritional periodisation reshape the gut microbiome of elite competitors, and where that reshaping translates into measurable performance.

Sport-specific microbial signatures

Endurance athletes — cyclists, runners, race walkers, trail runners — consistently showed enrichment of Veillonella, a lactate-utilising genus that converts exercise-derived lactate into propionate. Power athletes (MMA, freestyle wrestling, rowing, swimming) trended toward higher Bacteroidaceae abundance. Team sports (basketball, volleyball, soccer) showed dynamic stability across competition and recovery phases rather than a fixed enterotype.

Why Veillonella matters for endurance

Scheiman and colleagues — cited in the review — demonstrated that lactate produced by skeletal muscle during high-intensity work enters the colonic lumen, where Veillonella ferments it into propionate. The propionate re-enters circulation and is used as a gluconeogenic substrate — the host literally fuels a bacterium that pays back in usable energy. Manor et al. corroborated a positive correlation between Veillonella abundance and vigorous physical activity.

The barrier, zonulin and overtraining

Strenuous or poorly periodised training shifts the microbiome toward dysbiosis and raises intestinal permeability via zonulin-mediated tight-junction loosening (Fasano). The result is increased systemic inflammation, slower recovery and a documented connection between overtraining and a non-functional gut barrier. A balanced microbiota — and an intact barrier — reduces reactive oxygen species and inflammatory markers, attenuating macromolecular damage from training stress.

Nutrition and probiotics as modulators

Carbohydrate and fat periodisation, fibre intake and targeted probiotic supplementation all shifted microbial composition in the included trials, often synergistically with the training stimulus. Jäger et al. found that probiotics may improve GI symptoms, immune resilience and training-day availability — though effects remain strain-specific.

Methodological caveats

Sample sizes in elite-athlete studies ranged from 1 to 84 and interventions from 7 days to 20 weeks. Heterogeneous sequencing approaches (16S rRNA vs shotgun metagenomics) and the practical constraints of working around competition calendars limit direct comparison. The review explicitly calls for longer, better-powered trials with consistent species-level resolution.

What this means for performance teams

For federations and elite clubs the takeaway is concrete: a generic 16S phylum-level snapshot will miss the species that actually predict endurance and recovery. Species-level NGS — paired with periodised nutrition and a targeted probiotic strategy — is the operating model the literature now points toward. For a broader synthesis of how exercise and the microbiome interact, see our overview of the athlete gut microbiome and its relevance to health and performance.

Reference: Carlone J, Parisi A, Fasano A. The performance gut: a key to optimizing performance in high-level athletes: a systematic scoping review. Front Sports Act Living. 2025;7:1641923. doi.org/10.3389/fspor.2025.1641923