A study published in The Lancet (November 20, 1982; 1115–1117) examined the role of food sensitivity in irritable bowel syndrome (IBS) using a three-part experimental design.
In the first phase, 25 patients with IBS followed a strict elimination diet. For one week, participants consumed a highly restricted diet consisting of a single type of meat and one type of fruit. If IBS symptoms resolved, foods were reintroduced one at a time, at a rate of one food per day, until symptoms recurred. When a food appeared to provoke symptoms, subjects were challenged with that food on three separate occasions to confirm the response.
Six patients became symptom-free during the elimination phase. In the second part of the study, these patients were hospitalized for four days and fed only foods that had not previously triggered symptoms, with the same menu provided daily. Breakfast meals were administered as double-blind food challenges.
In the third phase, five patients were admitted to the hospital on two occasions, four weeks apart. During each admission, symptom-triggering foods were disguised and administered twice daily in a soup. Foods most commonly associated with symptom recurrence included wheat, corn, dairy products, coffee, tea, and citrus fruits.
Both the double-blind and single-blind challenges confirmed that specific foods provoked IBS symptoms in these patients. Measurements of plasma glucose, histamine, immune complexes, hematocrit, eosinophil count, and breath hydrogen excretion showed no significant changes following food challenges. In contrast, rectal prostaglandin E₂ (PGE₂) levels increased after exposure to trigger foods. In an additional five patients, rectal PGE₂ levels correlated with increased wet fecal weight.
The authors concluded that food intolerance associated with prostaglandin production plays an important role in the pathogenesis of IBS, at least in a subset of patients.
