Distinct microbiome composition and metabolome exists across subgroups of elite Irish athletes irrespective of diet

The gut microbiome has begun to be characterised in athlete groups, albeit, to date, only across a subset of sports. This study aimed to determine if the gut microbiome and metabolome differed across sports classification groups among elite Irish athletes, many of whom were participating in the 2016 Summer Olympics. Faecal and urine samples were collected from 37 international level athletes. Faecal samples were prepared for shotgun metagenomic sequencing and faecal and urine samples underwent metabolomic profiling. Dietary intake data was collected using food frequency questionnaires and translated into daily intakes using FETA (Food Frequency Questionnaire European Prospective Investigation into Cancer and Nutrition Tool for Analysis). Differences were observed in the composition and functional capacity of the gut microbiome of athletes across sports groups that were distinguished on the basis of the level of dynamic and static components. The microbiomes of athletes participating in sports with a high dynamic component were found to be most distinct compositionally, while those of athletes participating in sports with high dynamic and static components were the most functionally distinct. Additionally, both microbial (faecal) and human (urine) derived metabolites were found to vary between sports classification groups. In particular cis-aconitate, succinic acid and lactate, in urine samples, and creatinine, in faeces, were found to be significantly different between groups. These differences were evident despite the absence of significant differences in diet. Differences in the gut microbiome and metabolome between groups, in the absence of dietary changes, indicate a role for training load or type as a contributory factor. Further exploration of this hypothesis has the potential to benefit athletes, aspiring athletes and the general public.