The Effects of FODMAPs in Patients With Irritable Bowel Syndrome (Sens-IBS)

The Effects of Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols (FODMAPs) in Patients With Irritable Bowel Syndrome

Patients with Irritable Bowel Syndrome (IBS) often link their symptoms to foods. Interest in dietary management recently increased, including the use of a low FODMAP diet. To investigate relation of FODMAPs and IBS, a randomized, double-blind, cross-over trial will be carried out in adult (>18) patients with IBS according to Rome IV criteria. The aim is to assess low FODMAP diet versus moderate/high FODMAP diet in IBS patients.

The study is a randomized, double-blind, cross-over trial. The aim is to assess the effects of low fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAP) diet compared to moderate/high FODMAP diet in IBS patients on gastrointestinal symptoms and psychological factors. The primary hypothesis is that the low FODMAP diet decreases gastrointestinal symptoms compared to moderate/high FODMAP diet, and that this change is accompanied with reduced psychological distress. IBS patients (Rome IV) are challenged with FODMAPs in this randomized, double-blinded, cross-over study. The subjects will start with the low FODMAP diet or moderate/high FODMAP diet and cross over to the other intervention (both for 7 days). In between the interventions, there is a wash-out period of at least 14 days. The subjects will receive ready-made meals from the hospital kitchen (lunch and dinner) and in between snacks. The subjects are instructed to buy breakfast themselves and the subjects will receive information on which other foods to avoid, without mentioning 'FODMAPs'. The subjects will follow their usual diet (as before initiation of the study) during the wash-out period. Primary outcomes are change in gastrointestinal symptoms, assessed by questionnaires, including IBS Severity Scoring System (IBS-SSS) (7-10 day recall and modified daily) and Gastrointestinal Symptom Rating Scale -IBS (GSRS-IBS). A 50-point reduction in IBS-SSS indicates clinical response. Bacterial fermentation (exhaled hydrogen and methane) and visceral sensitivity will be measured using the Lactulose Nutrient Challenge Test. Secondary outcomes are change in psychological factors and assessed by questionnaires, including Central Sensitization Index (CSI), Hospital Anxiety and Depression Scale (HADS), Patient Health Questionnaire (PHQ)-15 and Visceral Sensitivity Index (VSI).

The randomization was done by employees of the hospital that were otherwise not involved in the study by drawing concealed envelops. The interventions were meal boxes which looked similar.

The subjects will follow the moderate/high FODMAP diet as the first intervention, and the low FODMAP diet as the second intervention. The subjects will follow both interventions for seven days.

The subjects will follow the low FODMAP diet as the first intervention, and the moderate/high FODMAP diet as the second intervention. The subjects will follow both interventions for seven days.

The subjects will obtain meal boxes prepared in the hospital kitchen with a moderately high FODMAP content (23 grams/day)

The subjects will obtain meal boxes prepared in the hospital kitchen with a low FODMAP content (<5 grams/day)

Change in Irritable Bowel Syndrome-Severity Scoring System (IBS-SSS) (7-10 days recall questionnaire)

Irritable Bowel Syndrome-Severity Scoring System (IBS-SSS) is a validated questionnaire that incorporates typical IBS symptoms such as abdominal pain, abdominal distension and bowel dysfunction, as well as quality of life. Subjects rated their symptoms on a visual analogue scale. The maximum achievable score is 500 points (sum of the 5 scales). A reduction in the total IBS-SSS score of at least 50 points is considered to indicate a clinically significant improvement in symptoms. The scale can also be used to classify IBS symptoms severity: <75 points (no symptoms), 75-175 points (mild symptoms), 175-300 points (moderate symptoms) and >300 points (severe symptoms). Measured after both dietary periods and at baseline of both periods.

Irritable Bowel Syndrome-Severity Scoring System (IBS-SSS) is a validated questionnaire that incorporates typical IBS symptoms such as abdominal pain, abdominal distension and bowel dysfunction, as well as quality of life. Subjects rated their symptoms on a visual analogue scale. The maximum achievable score is 500 points (sum of the 5 scales). A reduction in the total IBS-SSS score of at least 50 points is considered to indicate a clinically significant improvement in symptoms. The scale can also be used to classify IBS symptoms severity: <75 points (no symptoms), 75-175 points (mild symptoms), 175-300 points (moderate symptoms) and >300 points (severe symptoms). Measured after both dietary periods and at baseline of both periods.

Change in Gastrointestinal Symptom Rating Scale - Irritable Bowel Syndrome (GSRS-IBS) measures symptom severity and symptom frequency in IBS patients and is a reliable and validated questionnaire. Thirteen questions are evaluated and rated from 1 (no discomfort at all) to 7 (very severe discomfort) on a Likert scale. The total scores can range from 13 to 91 (sum of the domains). The GSRS-IBS evaluates 5 domains: abdominal pain, bloating, constipation, diarrhea and satiety. Measured after both dietary periods and at baseline of both periods.

The Hospital Anxiety and Depression Scale (HADS) contains 7 items for depression and 7 for anxiety. Each item is scored from 0 to 3, and therefore the total score per sub-scale can range from 0 to 21. When subjects score >10 on 1 or 2 of the sub-scales, clinically significant psychological distress (anxiety or depression) is likely present. Measured after both dietary periods and at baseline of both periods.

The (PHQ-15) is a validated questionnaire that evaluates 15 somatic symptoms and can be used as a screening tool for somatization in clinical research. The maximum score for men is 28 and 30 for women due to a question about menstrual problems. Measured after both dietary periods and at baseline of both periods.

The Visceral Sensitivity Index (VSI) is a validated and reliable psychometric instrument which assesses gastrointestinal symptom-specific anxiety. The VSI contains 15 items that are scored from 0 to 5, therefore the total score can range from 0 to 75. Higher scores indicate more severe gastrointestinal symptom-specific anxiety. Measured after both dietary periods and at baseline of both periods.

Visceral Sensitivity and Bacterial Fermentation measured by the Lactulose Nutrient Challenge Test. To assess if visceral sensitivity and/or bacterial fermentation are predictors of clinical response to the low FODMAP diet or clinical worsening to the moderate/high FODMAP diet.

Fecal microbiota analysis using 16 S RNA technique and Dysbiosis Test. Analyses will be done on samples from before and after both dietary periods.

Frozen urine/serum/fecal samples will be analyzed in the future by gas/liquid chromatography mass spectrometry (metabolomics) analysis.Analyses will be done on samples from before and after both dietary periods.

Inclusion Criteria: Adult patients with IBS according to Rome IV criteria Exclusion Criteria: allergy or documented intolerance to food severe cardiovascular disease severe hepatic disease severe neurological disease severe psychiatric disease celiac disease inflammatory bowel diseases diabetes bowel dysfunction related to previous surgery pregnant or lactating women use of antibiotics within four weeks before inclusion strict avoidance of foods

Algera JP, Demir D, Tornblom H, Nybacka S, Simren M, Storsrud S. Low FODMAP diet reduces gastrointestinal symptoms in irritable bowel syndrome and clinical response could be predicted by symptom severity: A randomized crossover trial. Clin Nutr. 2022 Dec;41(12):2792-2800. doi: 10.1016/j.clnu.2022.11.001. Epub 2022 Nov 4.