Table 1 Characteristics of the FODMAPs studies included in the systematic review

Bohn 2015 [20]

Randomized, single- blind, trial

Adults aged 18–70 y (N = 75) IBS

Low FODMAPs diet

4 wks

Severity of IBS symptoms; Instruments: IBS-SSS

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

High

Chumpitazi 2015 [22]

Randomized, double-blind, cross-over study, with wash-out

Children aged 7–17 y

(N = 33) IBS

Low FODMAPs diet

2 days

Children pain episodes frequency; Instruments: Pain and Stoll Diary

17 children began with the TACD, and 16 began with the low FODMAP diet; children had fewer daily abdominal pain episodes during the low FODMAP as compared to the TACD dietary intervention [1.1 ± 0.2 vs. 1.7 ± 0.4 pain episodes per day, respectively; P < 0.05].

Moderate

de Roest 2013 [33]

Prospective observational study

Adults (aged non specified) (N = 90) IBS

Low FODMAPs diet

6 wks

Improvement of GI symptoms including abdominal pain, bloating, flatulence and diarrhoe; Instruments: GSRS (7-point Likert scale)

90 patients with IBS (47%) completed the whole study. Symptoms significantly improved 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 to diet and improvement in individual GI symptoms

Low

Escobar 2014 [45]

Retrospective study

Children and adults aged 2–19 y

(N = 222) RAP

Low-fructose diet

2 months (not clearly specify)

Improvement of abdominal pain; Instruments: Pain scale score

93 of 121 patients with BTH positive (76.9%) reported resolution of symptoms on a low-fructose diet (P < 0.0001) respect to 55 of 101 patients (54.4%) with negative BHT for fructose (P = 0.37).

Low

Gijsbers 2012 [42]

Prospective study with DBPC test of provocation

Children aged 4–16 y (N = 220) RAP

Low-lactose and/or fructose diet

3 day of provocation test

Disappearance of abdominal pain with elimination, recurrence with provocation and disappearance with re- elimination; Instruments: not specify

Pain disappeared upon elimination in 24/38 patients with lactose malabsorption, and in 32/49 with fructose malabsorption. Open provocation with lactose and fructose was positive in 7/23 and 13/31 patients. DBPC provocation in 6/7 and 8/13 patients, was negative in all. However, several children continued to report abdominal symptoms upon intake of milk or fructose.

Low

Gomara 2008 [43]

Prospective study

Children aged 7–17 y

(N = 32) FGIDs

Low-fructose and low-sorbitol diet

2 months

Improvement in their GI symptoms; Instruments: not specify

Among the group with positive fructose breath test results, 9 of 11 patients (81%) reported almost immediate improvement in their symptoms; only abdominal pain and bloating were significantly reduced (P < 0.05)

Low

Gremse 2003 [41]

Randomized, double-blind, cross-over study

Children aged 3–17 y

(N = 30) RAP and lactose maldigestion

Low-lactose diet

2 wks

Improvement in their GI symptoms; Instruments: Symptoms Daily Diary

Significant increase in abdominal pain experienced by study participants during the lactose ingestion period when compared to the lactose-free period

Moderate

Halmos 2014 [28]

Randomized, controlled, single-blind, cross-over trial

Adults aged 23–60 y (N = 38) IBS

Low FODMAPs diet

21 days

Improvement in their GI Symptoms; Instruments: Daily symptom scale; VAS

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.Bloating, pain, and passage of wind also were reduced while IBS patients were on the low-FODMAP diet, but diarrhea-predominant IBS was the only subtype with altered fecal frequency and King’s Stool Chart scores.

Moderate

Houstoft 2016 [31]

Randomized Double-blind, placebo controlled, cross-over study

Adults aged 18–52 y (N = 20) diarrhea-predominant or mixed IBS

Low FODMAPs diet

9 wks

Improvements in GI symptoms; Instruments: IBS-SSS

There was a significant improvement in all IBS symptoms after 3 weeks of LFD with a mean reduction in IBS-SSS total score of 163.8.

When supplementing the LFD with FOS or placebo, significantly more participants reported symptom relief in response to placebo (80%) than FOS (30%; P = .013).

Moderate-High

Lebenthal 1981 [40]

Prospective study

Children aged 6–14 y

(N = 69) RAP

Low-lactose diet

12 months

Improvement in RAP;

Instruments: Symptoms Diary

After 12 months of elimination diet symptoms of RAP resolved in 6/15 (40%)lactose malabsorbers, 5/13 (38,4%)

lactose absorbers and in 5/12 (41.7%) lactose absorbers in regular diet

Low

Maagard 2016 [36]

Retrospective study

Adults aged 18–85 y (N = 180)

IBS and IBD

Low FODMAP diet

16 months

Improvement of symptoms and stool pattern; Instruments: Questionnaire, IBS SSS, stool pattern

Eighty-six per cent of patients on LFD reported either partial (54%) or full (32%) efficacy with greatest improvement of bloating (82%) and abdominal pain (71%). After dietary intervention, the proportion of patients producing normal stools increased, with 41% in the IBS group (P < 0.001)

Low

Ong 2010 [30]

Randomised, single-blind, cross-over study

Adults aged 22–68 y (N = 30) IBS

low FODMAPs-diet

2 days

Improvement of symptoms; Instruments: GI symptoms questionnaire; food diares; breath test

All symptoms were significantly worsened with high FODMAP diet in patients with IBS. Dietary FODMAPs induce prolonged hydrogen production in the intestine that is greater in IBS patients

Moderate-High

Pedersen 2014 [29]

Randomised unblinded controlled trial

Adults aged 18–74 y (N = 123)

Low FODMAPs diet

6 wks

Changes in IBS symptoms and quality of life; Instruments: IBS-SSS and IBS-QoL

Overall there was a significant reduction of IBS-SSS mean ± SD in all patients from baseline to week 6, mean IBS-SSS score 77 ± 104, P < 0.01, as well as in each treatment group (LFD, P < 0.001, LGG, P < 0.01 and ND, P = 0.03).At week 6, comparing mean IBS-SSS between all three groups, a statistically significant reduction in the IBS-SSS was observed in LFD and LGG groups compared to the ND group, mean IBS-SSS 133 ± 122 vs 68 ± 107, 133 ± 122 vs 34 ± 95, P < 0.01

Moderate-High

Pedersen 2014 [32]

Prospective, uncontrolled pilot study

Adults aged 18–74 y

(N = 19) IBS

Low FODMAPs diet

6 wks

Changes in IBS symptoms and quality of life; Instruments: IBS-SSS and 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

Moderate

Staudacher 2011 [21]

Prospective, controlled, study

Adults aged 26–50 y

(N = 82) IBS

Low FODMAPs diet

Unclear

Improvement of GI symptoms: Instruments: validated IBS Global Improvement Scale (7-point Likert scale); Four statements on satisfaction with symptom response and dietary advice

Significantly more patients in the low FODMAP group compared to the standard group reported improvements in bloating (low FODMAP 82% versus standard 49%, P = 0.002), abdominal pain (low FODMAP 85% versus standard 61%, P = 0.023) and flatulence (low FODMAP 87% versus standard 50%, P = 0.001). There were no significant differences in the proportion of patients reporting improvement in constipation between groups.

Moderate-Low

Staudacher 2012 [27]

Randomized, controlled tiral

Adult aged 18–65 y

(N = 41) IBS

Low FODMAPs diet

4 wks

Improvement of GI symptoms;

Instruments: symptom diary based on the GI Symptom Rating Scale

All 41 patients were included for ITT and 35 in the PP analysis.At follow-up, more patients inthe intervention group reported adequate symptom control with ITT (68% vs 23%) and for PP (81% vs 26%)

Moderate

Valeur 2016 [35]

Prospective study

Adults aged > 18 y

(N = 63) IBS

Low FODMAPs diet

4 wks

Decreased GI symptoms and evaluation of Short-chain fatty acids (SCFAs); Instruments:IBS-SSS

Sixty-three patients completed the study. Following the dietary intervention, IBS-SSS scores improved significantly (p < 0.0001). Total SCFA levels were reduced in fecal samples analyzed both at baseline (p = 0.005) and after in vitro fermentation for 24 h (p = 0.013).

Low

Wildersmith 2017 [34]

Prospective study

Adults aged 26-58y

(N = 653) FGIDs

Low FODMAPs diet

6–8 wks

Decreased global symptoms; Instruments: A nonstandard questionnaire on abdominal symptoms (10-point Likert scales) Bowel and dietary habits

237 of 312 (76%) patients completed the studyOver 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

Moderate

Wintermeyer2012 [44]

Prospective study

Children aged 3–14 y

(N = 75) RAP

Low-fructose and low-sorbitol diet

4 wks

Improvement frequency and intensity of abdominal pain; Instruments: nonstandard questionnaire

A median decline of weekly pain frequency from 4 (mean 3.64 + 1.6) before diet to 1 (mean 1.46 + 1.4; p < 0.001) under fructose restriction was documented. The intensity of pain decreased from median 6 (mean 5.83 + 2.0) before intervention to median 3 (mean 3.4 + 2.5; p < 0.001) with diet. Several additional life quality-influencing parameters such as daily stool frequency, nausea, problems to fall asleep, missed school days also improved significantly.

Moderate