Irritable Bowel Syndrome: Histamine produced by gut bacteria causes abdominal pain

The research team observed patients with irritable bowel syndrome for several months and found that their stools contained particularly high levels of histamine when they were in severe pain. Klebsiella aerogenes were the most important histamine producer in germ-free mice into which the intestinal flora of IBS patients was transferred. The bacteria converted histidine, which is found in animal and vegetable protein, into histamine. This then activates the immune system and attracts mast cells to the gut, causing them to release more histamine and other messengers that cause inflammation and pain.

He found that bacterial production of histamine was significantly reduced when the animals were fed a diet low in fermentable carbohydrates. This may explain why some patients with irritable bowel syndrome benefit from changing the diet or following a FODMAP diet that avoids such carbohydrates. Some also benefit from treatments with mast cell stabilizers or antihistamines.

Professor Giada de Palma from McMaster University in Canada is optimistic about the findings: “Now that we know how histamine is produced in the gut, we can identify and develop treatments that target histamine-producing bacteria.”

Source: DOI 10.1126 / scitranslmed.abj1895