Symptom pattern following a meal challenge test in patients with irritable bowel syndrome and healthy controls

Background: Patients with irritable bowel syndrome (IBS) often complain of worsening of symptoms after meal intake. Meal challenge tests have previously been used to study symptoms and pathophysiology in functional dyspepsia. Objective: The objective of this article is to evaluate differences in gastrointestinal (GI) symptom response to a standardized meal test in IBS compared to healthy controls. Methods: We included 67 patients with IBS and 16 healthy controls. After an overnight fast the subjects were served breakfast (540 kcal; 36% fat, 15% proteins, 49% carbohydrates; 8.9 g fiber). They completed visual analog scales assessing severity of six GI symptoms (abdominal pain, bloating, discomfort, nausea, gas, fullness) before breakfast and every 30 minutes up to 240 minutes after breakfast. The patients also completed a questionnaire (IBS-SSS) to assess IBS symptom severity during the preceding week. The course of symptom scores over time was analyzed using mixed models. Results: The meal was well tolerated and all subjects completed the test period. In patients, significant effects of time (initial increase to a maximum, followed by a return to baseline) were found for fullness, bloating, nausea and discomfort (all p values < 0.01 for linear, quadratic and third-order effect of time). In IBS patients, an independent significant association between IBS-SSS scores and all postprandial symptoms, except for nausea, was found (all p < 0.01). In controls, a significant linear, quadratic and third-order effect of time (all p < 0.0001) was found for fullness only. The difference in time course for bloating and discomfort between IBS patients and controls was confirmed when comparing the groups directly (significant time-by-group interaction effects, all p < 0.05), but not for nausea. On average, IBS patients scored significantly higher than controls on all symptoms, except for nausea (significant main effects of group, all p< 0.05). Conclusions: A standardized meal test seems to be a promising tool to study the symptom pattern in IBS and potentially to follow the effect of interventions.