Mediterranean diet enhances endurance training adaptation through gut microbiota-derived short-chain fatty acids

The concept of the gut microbiota and short-chain fatty acids (SCFAs) has emerged. Although the Mediterranean diet has beneficial effects on the composition of the gut microbiota and the production SCFA, it has not been shown to affect the adaptation induced by endurance exercise. This study aimed to investigate the effect of the Mediterranean diet on the production of SCFA and VO₂max in endurance athletes.

This was a 12-week randomized controlled trial among 60 competitive endurance athletes who were randomly assigned to either a Mediterranean diet group (n = 30) or a control group (n = 30). All participants followed a common training program. The composition of gut microbiota was analyzed using 16S rRNA gene sequences, and the concentration of SCFAs was analyzed using gas chromatography-mass spectrometry. The outcome measure was the change in VO₂max. Mediation analysis was performed to examine the role of plasma SCFAs as a mediator of the association between diet and performance.

Fifty-five participants were included in the study. The Mediterranean diet showed a significant increase in alpha diversity (Shannon index: +11.2%, p = 0.002) and in the abundance of Faecalibacterium and Roseburia. Plasma propionate (+42.1%, p = 0.005) and butyrate (+57.9%, p = 0.002) increased significantly, while acetate showed a non-significant trend. VO₂max improvement was greater in the Mediterranean diet group (2.4 ± 1.6 vs. 1.3 ± 1.4 mL/kg/min; adjusted difference: 1.1 mL/kg/min; 95% CI: 0.3-1.9; p = 0.006; Cohen's d = 0.73). Plasma propionate (r = 0.38, p = 0.004) and butyrate (r = 0.42, p = 0.001) changes correlated positively with VO₂max improvement. Mediation analysis indicated plasma propionate accounted for 23% of the dietary effect on VO₂max. Results were consistent in intention-to-treat analysis (adjusted difference: 1.0 mL/kg/min; 95% CI: 0.2-1.8; p = 0.012; Cohen's d = 0.68).

Mediterranean diet intervention alters gut microbiota composition, increases plasma SCFA concentrations, and improves endurance exercise adaptation. These findings indicate that the gut-muscle axis may represent an intervention target for optimizing sports performance.