Table 4.

Randomized control trials of low FODMAP diet in adults with IBS

Study	Study design	Participants recruited for the study	Inclusion and exclusion criteria	Dietary intervention	Outcome measures	Key results
Interventional studies
Shepherd et al57	Double-blinded, randomized, quadruple arm, placebo-controlled rechallenge trial 2 weeks maximum test period	26 participants with IBS and fructose malabsorption Median 38 years 85% female Previously good GI symptom control while on low FODMAP diet	IBS (Rome II criteria) Excluded celiac disease, IBD, other concomitant serious morbidity or if taking medications potentially influencing GI symptoms	All participants on supplied low FODMAP diet followed by rechallenge of graded doses of fructose, fructans, fructose, and fructan mix or glucose (control) drinks with meals >10-day washout between tests	Mean score of individual symptoms using 100-mm VAS A global symptom question asked at the end of each highest dose consumed for the drinks	Symptoms induced in a dose-dependent manner when drinks containing fructose (70%), fructans (77%), and a combination (79%) were given as opposed to 14% symptom induction in those receiving glucose drink
Ong et al47	Randomized, single-blinded, crossover intervention trial 2 days of each diet	15 healthy subjects Mean 23 years 60% female 15 subjects with IBS mean 41 years 87% female	IBS (Rome III criteria) No medically significant comorbidities, not pregnant, and had no prebiotic supplements or antibiotics for >8 weeks prior to the study No prior IBS education	Provided low (9 g/d) and high (50 g/d) FODMAP diet All food matched for total energy, starch, protein, fat, indigestible long-chain CHO Dietary fiber and resistant starch kept constant 7-day washout period before crossover	Breath hydrogen levels A questionnaire consisting of five general GI symptoms Food diaries	All subjects completed the study All symptoms were significantly worsened with high FODMAP diet in patients with IBS Only increased flatus production was reported by healthy volunteers
Staudacher et al56	Randomized, control trial 4 weeks of either diet	41 patients with IBS Mean age 35 years 66% female ITT (68% vs 23%) and for PP (81%	IBS (Rome III criteria) IBS with bloating and/or diarrhea Excluded other major GI conditions, constipation as predominant IBS symptom, pregnancy, lactation, use of probiotics, prebiotics, lactulose 4 weeks prior to study or changes in IBS meds prior to/during study	An experienced dietitian-led advice: • Low FODMAP diet (19) or control group with habitual diet (22) for 4 weeks • Weekly follow-up via email or telephone	Validated GSRS Stool output Food diaries	All 41 patients were included for ITT and 35 in the PP analysis At follow-up, more patients in the intervention group reported adequate symptom control with vs 26%)
Halmos et al55	Randomized, controlled, single-blind crossover trial 21 days of either diet	45 participants 33 IBS (mean age 41 years, 70% female) 12 healthy individuals (mean age 31 years, 75% female)	IBS (Rome III criteria) Healthy controls without GI symptoms Exclusion of celiac disease, previous abdominal surgery, and significant other diseases No previous dietary or other treatments for IBS and no pharmacological agents	1 week of habitual diet followed by low FODMAP diet (<0.5 g FODMAPs/meal) or typical Australian diet All foods were provided (three meals and three snacks) At least 21 days of washout period	100-mm VAS Fecal assessment Breath hydrogen Food diaries	30 IBS participants (91%) and 8 controls (67%) completed the study 70% IBS subjects had lower overall GI symptom scores on low FODMAP diet compared with typical and subjects’ habitual diet Similar results with individual symptoms Minimal or unaltered symptoms in controls
Pedersen et al59	Randomized, unblended controlled trial Web-based questionnaires completed weekly during 6 weeks intervention	123 patients with IBS Median age 37 years 73% female	IBS (Rome III criteria) Negative colonoscopy, celiac, and lactose intolerance gene Excluded low BMI <18, alarming symptoms such as weight loss > 5 kg, anemia, fever, colorectal cancer, and other significant disease	6 weeks of: • 42 low FODMAP diet or • 40 normal Danish/Western diet or • 41 normal diet and probiotics (Lactobaccillus rhamnosis GG) Low FODMAP diet advice by dietitians Published Australian high FODMAP list used	IBS-SSS IBS-QoL	34 (81%), 37 (92%) and 37 (90%) completed the low FODMAP, normal and probiotic diet, respectively A significant reduction in IBS-SSS in all three groups after 6 weeks from their baseline No significant reduction in IBS score in any groups for IBS-C type and no difference between normal diet and probiotics A significant reduction of IBS-SSS in low FODMAP and probiotic groups compared to normal diet IBS-QoL was statistically improved in all patients from baseline
Böhn et al58	Randomized, controlled, single-blind trial 4 weeks of either diet	75 patients with IBS Mean age 43 years 82% female	IBS (Rome III criteria), IBS-SSS ≥175 (moderate-to-severe symptoms) No excessively restrictive diet except low lactose diet. Allowed probiotic products and antidepressants Excluded severe cardiac, liver, neurologic or psychiatric disease, and other GI diseases (IBD, celiac disease)	Advised by experienced dietitians 38 – Diet A (low FODMAP diet) Information on foods to avoid and alternatives. 37 – Diet B (traditional IBS diet advice) Regular meals, healthy eating, avoid large meals, reduce fat intake, etc	IBS-SSS Stool diary 4 days food diary	33 (87%) low FODMAP and 34 (92%) traditional IBS diet group completed the study IBS symptom severity was significantly reduced in both groups compared to baseline; however, the score did not differ between the groups 19 (50%) low FODMAP group and 17 (46%) traditional IBS diet group responded to the interventions

Abbreviations: FODMAP, fermentable oligosaccharide, disaccharide, monosaccharide, and polyols; IBS, irritable bowel syndrome; CHO, carbohydrates; GI, gastrointestinal; GSRS, gastrointestinal symptom rating scale; ITT, intention to treat; PP, per-protocol; VAS, visual analog scale; QoL, quality of life; BMI, body mass index; IBS-SSS, irritable bowel syndrome symptom scoring system; IBS-C, constipation-predominant IBS; IBD, inflammatory bowel disease; VAS, visual analogue scale.