FODMAP meal challenge test: a novel investigation to predict response to low-FODMAP diet in non-constipating irritable bowel syndrome

Background: Though a low-FODMAP diet improves 50% irritable bowel syndrome (IBS) patients, regional dietary variations, vegetarianism, and long-term nutritional consequences challenge its implementation. We aimed developing a FODMAP meal challenge test (FMCT). We prospectively studied whether (i) high- than low-FODMAP foods produce more breath H₂ among IBS patients than controls; (ii) post-meal symptoms relate to breath H₂ ; and (iii) novel FMCT predicts response to a low-FODMAP diet?

Methods: Forty Rome III IBS and 20 healthy controls underwent an eight-hour H₂ breath test following a low- (rice, brinjal, corn, and banana [450 Kcal]) and a high-FODMAP meal (wheat, kidney bean, pulse, and card [450 Kcal]). Breath H₂ (every 15 min) and symptoms following low- and high-FODMAP meals were recorded. IBS-symptom severity scores were recorded every month for 3-months on low-FODMAP diet.

Results: Forty Rome III IBS (19 Rome IV positive) were comparable to 20 controls in age and gender. IBS patients (n = 39 excluding one H₂ non-producer) and controls produced more breath H₂ after high- (greater in IBS) than low-FODMAP meal. Post-meal symptoms were commoner in IBS (4/40 [10%] and 27/40 [67.5%] with low- and high-FODMAP, respectively [P < 0.00001]; none in healthy). IBS patients developing post-high-FODMAP meal symptoms produced greater H₂ (18 PPM [IQR 10.5-23] vs 6 [0-7.2]; P < 0.001). A positive FMCT (breath H₂ > 10 PPM above basal with symptoms following high-FODMAP food) had sensitivity, specificity, and diagnostic accuracy of 78.6%, 66.6%, and 75.6%, respectively, to predict low-FODMAP diet response.

Conclusions: The novel FMCT predicts response to a low-FODMAP diet in IBS.