Short-Term Effects of Low-FODMAP, NICE Dietary Advice, and Intermittent Fasting in Irritable Bowel Syndrome

Acibadem University90 enrolled

Overview

The goal of this clinical trial is to compare the short-term effects of three dietary approaches in adults with irritable bowel syndrome (IBS): a low-FODMAP diet, adapted National Institute for Health and Care Excellence (NICE) dietary advice, and adapted NICE dietary advice combined with 16:8 intermittent fasting. The main questions this study aims to answer are: How do these three dietary approaches affect IBS symptom severity after two weeks? How do these three dietary approaches affect IBS-related quality of life after two weeks? The researchers hypothesize that the low-FODMAP diet will produce the greatest short-term reduction in IBS symptom severity. The study will also explore whether adding 16:8 intermittent fasting to adapted NICE dietary advice provides additional benefit. Researchers will compare the three dietary groups to determine whether the changes in IBS symptoms and quality of life differ between the dietary approaches. Participants will: Follow one of the three dietary approaches for two weeks. Attend study visits at the beginning of the study, after one week, and after two weeks. Keep records of their food and fluid intake. Complete questionnaires about IBS symptoms, quality of life, anxiety, and depression. Record their stool form and frequency during the study.

Study Type

INTERVENTIONAL

Allocation

NON_RANDOMIZED

Purpose

TREATMENT

Masking

NONE

Enrollment

Conditions

Irritable Bowel Syndrome

Low-FODMAP DietBEHAVIORAL

Participants followed a researcher-designed low-FODMAP elimination diet for two weeks. The dietary intervention was delivered by a dietitian who had completed Monash University Low-FODMAP Diet Training. Foods containing fermentable oligosaccharides, lactose, excess fructose, and polyols were restricted. The reintroduction phase of the low-FODMAP diet was not implemented during the two-week study period.

Adapted NICE Dietary AdviceBEHAVIORAL

Participants followed adapted NICE dietary advice for two weeks. The recommendations included eating regular meals and avoiding prolonged fasting, drinking at least 2 liters of water per day, limiting

16:8 Intermittent FastingBEHAVIORAL

Participants followed a 16:8 intermittent fasting regimen in addition to adapted NICE dietary advice for two weeks. All meals were consumed within an 8-hour eating window, either from 11:00 to 19:00 or from 12:00 to 20:00, followed by a 16-hour fasting period. One or two snacks were permitted within the eating window. No specific restriction on fiber or FODMAP intake was applied.

Eligibility

Sex: ALLMin age: 18 YearsMax age: 65 Years

Medical Language ↔ Plain English

Inclusion Criteria: Adults aged 18-65 years Diagnosis of irritable bowel syndrome (IBS) according to the Rome IV criteria IBS subtype classified as IBS with constipation (IBS-C), IBS with diarrhea (IBS-D), or IBS with mixed bowel habits (IBS-M) Exclusion Criteria: Celiac disease Inflammatory bowel disease History of cancer Diabetes Kidney disease Pregnancy Current adherence to an elimination diet

Outcomes

Primary Outcomes

Change in Irritable Bowel Syndrome Symptom Severity

IBS symptom severity was assessed using the Irritable Bowel Syndrome Severity Scoring System (IBS-SSS). The total score ranges from 0 to 500, with higher scores indicating greater symptom severity. A reduction of at least 50 points was considered a clinically meaningful improvement.

Time frame: Baseline to 2 weeks

Secondary Outcomes

Change in Irritable Bowel Syndrome-Specific Quality of Life

IBS-specific quality of life was assessed using the Irritable Bowel Syndrome Quality of Life questionnaire (IBS-QOL). The questionnaire consists of 34 items across eight subscales. Scores are transformed to a 0-100 scale, with higher scores indicating better IBS-specific quality of life.