Efficacy of the low FODMAP diet for treating irritable bowel syndrome: the evidence to date

Figures & data

Table 1 Rome III diagnostic criteria for irritable bowel syndrome⁴

Recurrent abdominal pain or discomforta at least 3 days per month in the last 3 monthsb associated with two or more of the following:

1. Improvement with defecation

2. Onset associated with a change in frequency of stool

3. Onset associated with a change in form (appearance) of stool

Notes:

a Discomfort is an uncomfortable sensation not described as pain.

b Criteria fulfilled for the last 3 months with symptom onset of at least 6 months prior to diagnosis. Reprinted from Gastroenterology, 130(5), Longstreth GF, Thompson WG, Chey WD, Houghton LA, Mearin F, Spiller RC, Functional bowel disorders, 1480–1491, Copyright (2006), with permission from Elsevier.

Table 2 Examples of food high in FODMAPs and suitable low FODMAP alternatives

Types of sugars	High FODMAPs food	Low FODMAP alternatives
Oligosaccharides	FOS Grains: wheat-, rye-, and barley-based products Vegetables: onion, garlic, artichokes, leeks, beetroot, and savoy cabbage Fruits: watermelon, peaches, persimmon, prunes, nectarines and most dried fruit GOS Legumes: red kidney beans, baked beans, and soya beans Vegetables: beetroot and peas	Fruit: banana, most berries (except boysenberries and blackberries), grapes, lemon, lime, mandarin, orange, kiwi fruit, pineapple, passion fruit, and rhubarb Vegetables: capsicum, bok choy, green beans, parsnip, silverbeet, cucumber, carrots, celery, eggplant, lettuce, potatoes, yams, tomatoes, and zucchini Grains: wheat-free grains/flour, gluten-free bread or cereal products, and quinoa
Disaccharides	Lactose Dairy products: cows/goat milk, and yoghurt	Dairy products: lactose-free, almond or rice-based milk, yoghurt and ice cream, hard cheese, feta and cottage cheese
Monosaccharides	Fructose (in excess of glucose) Fruits: apples, pears, watermelon, mango, cherries, boysenberries and fruit juice from high-fructose foods Honey Sweeteners: high-fructose corn syrup Vegetable: asparagus and snap peas	Fruit: banana, grapes, honeydew, melon, kiwifruit, lemon, lime, mandarin, orange, passionfruit, paw paw, and most berries (except boysenberries and blackberries) Sweeteners: maple syrup and golden syrup
Polyols	Sorbitol Fruit: apples, pears, avocado, apricots, blackberries, nectarines, peaches, plums, prunes, and watermelon Mannitol Vegetables: sweet potato, mushrooms, cauliflower, and snow peas	Sweeteners: Maple syrup, and sugar (sucrose) Fruits: banana, grape, honeydew, melon, kiwifruit, lemon, mandarin, orange, passionfruit, and paw paw

Notes: Data from Monash University. Low FODMAP Diet Application. Available at: http://www.med.monash.edu/cecs/gastro/fodmap/. Android version accessed August 26, 2015.⁷²

Abbreviations: FODMAP, fermentable oligosaccharide, disaccharide, monosaccharide, and polyols; FOS, fructo-oligosaccharides; GOS, galacto-oligosaccharides.

Table 3 Observational studies 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
Observational studies
Shepherd and Gibson^Citation48	Retrospective study Follow-up telephone interview 2–40 months after dietary intervention (median 14 months)	62 consecutive patients with IBS and fructose malabsorption Median age 50 years 76% female	IBS (Rome II criteria) Positive fructose breath hydrogen test. Excluded celiac disease, IBD, and patients with known lactose malabsorption	1-hour dietitian-delivered advice: • avoidance of high free fructose foods in excess of glucose and high fructan foods • positive food choices • sample meal plan • coingestion of free glucose with fructose • avoiding foods rich in polyols	Dietary adherence Barriers to adherence Strategies used by patients Self-assessment of IBS symptoms using a –10 to 10 scale	48 (77%) adhered to the diet 46 (74%) responded positively in all abdominal symptoms Improvement in symptoms was significantly better in those adherent to the diet
Staudacher et al^Citation54	Nonrandomized, controlled study Questionnaire 2–6 months after dietary manipulation	82 consecutive patients with IBS Mean age 38 years 71% female	IBS diagnosis based on NICE criteria	Dietitian-led advice 39 – standard dietary advice (NICE guidelines) 43 – low FODMAP dietary advice: • suitable/unsuitable foods • meal plans • recipes adapted for the UK setting	Validated IBS Global Improvement Scale (7-point Likert scale) Four statements on satisfaction with symptom response and dietary advice	Overall symptom improvement greater in low FODMAP (86%) than standard diet (49%) group Greater benefits were seen in low FODMAP group for bloating, abdominal pain, and flatulence
Ostgaard et al^Citation49	Retrospective, case-control study Dietary guidance was given 2 years before the study Questionnaires sent by mail	63 patients with IBS without dietary guidance, 70 with dietary guidance, and 42 healthy controls Mean age 36 years 85% female	IBS diagnosis (Rome III criteria) Excluded organic GI disease, clinically significant systemic diseases, pregnant or lactating women, and abdominal surgeries, except appendectomy, Cesarean, and hysterectomy	Nurse-delivered dietary advice Two 1-hour sessions covering FODMAP avoidance	Validated MoBa FFQ SF-NDI IBS-QoL Validated Birmingham IBS Symptom scores (5-point Likert scale)	114 patients (65%) completed study (35 controls, 36 unguided, 43 guided patients with IBS) In guided patients with IBS, significant reduction in abdominal pain, but no significant differences in the total score or diarrhea/constipation Significant QoL improvement of guided patients with IBS compared to unguided patients
Mazzawi et al^Citation50	Prospective uncontrolled study Questionnaires before and 3–9 months after dietary intervention (median 4 months)	46 patients with IBS Mean age 35 years 76% female	IBS (Rome III criteria) Excluded organic GI disease, clinically significant systemic disease, pregnant or lactating, drug abuse, serious psychiatric diseases, abdominal surgeries, except appendectomy, cesarean section, and hysterectomy	Registered nurse with special training and experience. Three 45-minute sessions on dietary management	Validated Birmingham IBS symptom score IBS-QoL questionnaire SF-NDI Validated MoBa FFQ	17 (37%) completed study Reduced total IBS symptoms scores and significantly improved quality life following dietary guidance Significant improvement in abdominal pain, diarrhea, but not constipation Dietary guidance also resulted in adequate intakes of vitamins and minerals
de Roest et al^Citation51	Prospective uncontrolled study Questionnaires at baseline and follow-up (mean follow-up of 15.7±9 months) after dietary intervention	192 patients with IBS who had performed lactulose, fructose, and lactose breath testing Mean age 45 years 74% female	IBS diagnosed by a gastroenterologist or a colorectal surgeon Excluded significant GI comorbidities (IBD, celiac disease, significant diverticular disease or bowel resection)	Advice by a trained dietitian: • 1 -hour appointment and 30-minute follow-up 6 weeks later • lists of safe and restricted foods • recipes and shopping guide provided • reintroduction of restricted group of carbohydrates at follow-up	GSRS (7-point Likert scale) Assessment of safety and efficacy of the diet by email or post	90 patients with IBS (47%) completed the whole study. Significant improvement reported symptoms at follow-up (44% patients with improvement in abdominal pain, 38% in bloating, 38.5% in constipation, 60% in diarrhea) Significant positive correlation between adherence and improvement in individual GI symptoms
Wilder-Smithet al^Citation53	Prospective, uncontrolled study Questionnaires at baseline and 4 weeks after dietary intervention	1,372 patients with FGID (212 patients with IBS) who performed fructose and lactose breath testing Mean age 42 years 73% female	Classified into FGID subgroups according to (Rome III) 312 patients with positive fructose and lactose intolerance Excluded organic disease including celiac disease	Experienced dietitian-led advice: • standardized 4-week dietary modification • 1 week of diet low in saccharides and polyols followed by weekly introduction of fructose-, fructan-, inulin-, and lactose- containing food to individual tolerance	A nonstandard questionnaire on abdominal symptoms (10-point Likert scales) Bowel and dietary habits	237 of 312 (76%) patients completed the study Over 80% of patients attained adequate global symptom relief; 93% and 96% of patients with fructose or lactose malabsorption, respectively, 85% adequate relief in patients with diarrhea, 96% with bloating, and 51% with constipation
Pedersen et al^Citation52	Prospective uncontrolled pilot study Web-based questionnaires completed weekly during control and low FODMAP diet period (6 weeks each)	19 patients with IBS Median age 35 years 81% female	IBS (Rome III criteria) Excluded IBD, celiac disease, GI infection, and positive lactose intolerance gene test, history of food allergy, alarm symptoms, and other significant diseases	6 weeks of habitual diet (control) Dietitian-delivered low FODMAP diet: • 45-minute consultation • 6 weeks on the diet	IBS-SSS IBS-QoL	All 19 patients with IBS completed the study Significant improvement in IBS in control period and following dietary intervention period Low FODMAP diet further reduced symptoms (11 patients [57%] improved to mild IBS severity) Significant IBS-QoL change during low FODMAP diet period

Abbreviations: FODMAP, fermentable oligosaccharide, disaccharide, monosaccharide, and polyols; IBS, irritable bowel syndrome; FM, fructose malabsorption; IBD, inflammatory bowel disease; NICE, National Institute for Health and Clinical Excellence; MoBa FFQ, MoBa Food Frequency Questionnaire; SF-NDI, short-form nepean dyspepsia index; QoL, quality of life; IBS-SSS, irritable bowel syndrome symptom scoring system; GSRS, gastrointestinal symptom rating scale; GI, gastrointestinal; FGID, functional gastrointestinal disorder; ITT, intention to treat; PP, per-protocol.

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 al^Citation57	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 al^Citation47	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 al^Citation56	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 al^Citation55	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 al^Citation59	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 al^Citation58	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.

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