Effects of turmeric beverage consumption on gut microbial diversity during a professional soccer season: a pilot study

Turmeric is widely used as a dietary bioactive, but its longitudinal effects on the gut microbiome in elite athletes are unknown. We investigated this in a pilot cohort of 11 professional soccer players, followed across a competitive season using shotgun metagenomic profiling of fecal samples collected longitudinally. Players self-selected to control (no turmeric beverages) or intervention (one 60-mL turmeric beverage, consumed twice daily for six months) group, with fecal samples collected at baseline, 2 weeks post-baseline, and 6 months post-intervention. Analyses integrated Bayesian diversity modelling, exact permutation beta-diversity testing and exploratory paired change-score analysis. Turmeric exposure was associated with modest microbiome modulation, rather than large community-wide restructuring. Both species-level and functional alpha diversity exhibited a directional tendency toward reduction alongside high individual variability, while global beta-diversity analyses did not show robust intervention-control separation. Exploratory feature-level analyses identified structured but mixed responses, including a positive Blautia signal, a negative Alistipes signal, additional strain-level changes, such as Bifidobacterium catenulatum and Parabacteroides distasonis , and bidirectional pathway shifts. Taxonomy-function integration yielded several exploratory co-variation signals, including some meeting an exploratory false-discovery threshold, but these findings remained non-confirmatory in this small cohort. Turmeric was associated with a directional tendency toward reduction in both species and functional alpha diversity, without clear evidence of global community-wide restructuring. These results are hypothesis-generating and support targeted replication in longitudinal studies with larger sample sizes.