Researchers have identified why some people experience abdominal pain when they eat certain foods. The finding paves the way for more efficient treatment of irritable bowel syndrome and other food intolerances. The study, carried out in mice and humans, was published in the journal 'Nature'. Up to 20 per cent of the world's population suffers from irritable bowel syndrome (IBS), which causes stomach pain or severe discomfort after eating. This affects their quality of life. Gluten-free and other diets can provide some relief, but why this works is a mystery, since the patients are not allergic to the foods in question, nor do they have known conditions such as coeliac disease. Earlier work by Professor Boeckxstaens and his colleagues showed that blocking histamine, an important component of the immune system, improves the condition of people with IBS. An antigen is any molecule that provokes an immune response. Once the infection cleared, the mice were given ovalbumin again, to see if their immune systems had become sensitised to it. The results were affirmative: the ovalbumin on its own provoked mast cell activation, histamine release, and digestive intolerance with increased abdominal pain. This was not the case in mice that had not been infected with the bug and received ovalbumin. A larger clinical trial of the antihistamine treatment is currently underway.