In an innovative approach to colorectal cancer (CRC) prevention and treatment, scientists are studying ways to replace missing metabolites in patients prone to gut inflammation and CRC. A new study describes how administration of histamine-producing gut microbes to mice lacking the enzyme histidine decarboxylase (HDC) reduced inflammation and tumor formation. These results suggest that alteration of the gut microbiome with probiotics may become a new preventative or therapeutic strategy for patients at risk for inflammatory bowel disease (IBD)-associated CRC.