A study of over 1,700 individuals found differences in gut microbiome composition and function among patients with inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS). The results could help to distinguish between IBD and IBS patients and aid in the identification of new therapeutic targets. IBD and IBS are two of the most common gastrointestinal disorders, affecting up to 0.5% and 21% of the population worldwide, respectively. These conditions impair the quality of life of patients and are responsible for an economic burden of over $10 billion a year in the U.S. and Europe combined. Researchers have found that shifts in the gut microbiome are associated with both disorders, but few studies have fully profiled the community of gut bacteria present in IBD and IBS patients. To bridge this gap, Arnau Vich Vila et al. sequenced stool samples from 355 IBD patients, 412 IBS patients and 1,025 controls. They identified groups of bacteria that were associated with IBD and IBS and saw that both patient groups harbored a reduced diversity of beneficial species and an increased diversity of disease-causing species. Furthermore, bacterial growth rates were altered in nine species in IBD patients and one species in IBS patients, and both groups displayed a higher abundance of proteins associated with antibiotic resistance. The authors then combined their data with machine learning techniques to create a model that could discriminate between IBD and IBS, but say that further studies should validate the model's accuracy and better characterize the microbial pathways at play.