HRH2 and inflammatory bowel disease: A comprehensive metagenomic study has identified 117 histamine-secreting bacteria that are significantly enriched in inflammatory bowel diseases (IBD) patients with histamine-sensitivity inducing symptoms like headaches, itching, and digestive discomfort.24–26 In this context, certain probiotics can be involved in the production and metabolism of histamine reducing intestinal inflammation through the activation of the histamine H2 receptor.27