and lower abundance of the phylum Synergistetes compared to healthy controls, but also identified the host-microbial pathway of purine metabolism as an important player in the pathophysiology of IBS.14 They identified hypoxanthine that was decreased in IBS likely due to an increased xanthine dehydrogenase/oxidase activity from both the microbiome and the host, suggesting a possible therapeutical target for this subset of IBS patients. Here, XDH is linked to irritable bowel syndrome.