The impact of a competitive event and the efficacy of a lactic acid bacteria-fermented soymilk extract on the gut microbiota and urinary metabolites of endurance athletes: An open-label pilot study

Abstract

Diet and exercise can alter the gut microbiota, but recent studies have assessed the impact o f athletic competition on gut microbiota and host metabolites. We designed an open-label pilot study to investigate the effects o f both official competition and a multi-strain lactic acid bacteria-fermented soymilk extract (LEX) on the gut microbiota in Japanese college endurance athletes. The analysis o ffecal 16S rRNA metagenome and urinary metabolites was used to identify changes in gut microbiota composition and host metabolism. When the fecal microbiota were investigated before and after a race without using o f a supplement (preobservation period), there was an increase in the phylum Firmicutes and decrease in Bacteroidetes. However, no changes in these phyla were seen before and after a race in those who consumed LEX. Before and after LEX ingestion, changes in urinary metabolites included a significant reduction in yeast and fungal markers, neurotransmitters, and mitochondrial metabolites including the TCA cycle. There were several correlations between urinary metabolites and the composition o f fecal microbiota. For example, the level of tricarballylic acid waspositively correlated with the composition ratio o fphylum Firmicutes (Pearson’s r=0.66; p<0.01). The bacterial species Parabacteroides distasonis was also found to correlate moderately with several urinary metabolites. These findings suggest two possibilities. First, endurance athletes experience significantfluctuations in gut microbiota after a single competition. Second, LEX ingestion may improve yeast andfungal overgrowth in the gastrointestinal tract and enhancing mitochondrial metabolic function.