Brief Summary :

The goal of this clinical trial is to investigate the effects of differing FODMAP diets on gut microbiota, gut barrier function, symptom severity, quality of life, and psychological status in FGID patients. The main question it aims to answer is :

How does diets with differing FODMAP content affect the gut microbiota, gut barrier function, symptom severity, psychological status and quality of life in patients with FGID ? Researchers will compare low FODMAP diet, Gentle FODMAP diet and Traditional Dietary Advice (NICE guidelines) to see which diet is more suitable and effective for Malaysian FGID patients.

Participants will :

Be given either low FODMAP diet, Gentle FODMAP diet or Traditional Dietary Advice intervention and will be required to follow the intervention for two weeks.

Be required to provide stool and blood samples during baseline and intervention Record 4 day food diary and complete assessing questionnaires during baseline and intervention

Functional Gastrointestinal Disorder (FGIDs), including irritable bowel syndrome (IBS) and functional dyspepsia (FD), are prevalent conditions that effects about 40% of world population and 21% of Malaysian population. They represent a significant health burden, impacting patients' quality of life. While the low FODMAP diet is effective in managing FGID around the western region, there is limited research done on comparing the impacts of diets with differing FODMAP content on symptom severity, quality of life, gut microbiota and gut barrier function of FGID patients in the Asian region as low FODMAP is restrictive. Therefore, conducting a randomised controlled trial is vital in measuring the effectiveness of diet with differing FODMAPs on FGID patients.

The objectives of this study are :

• To determine the effect of FODMAPs restriction on the gut microbiota abundance and diversity in FGID patients
• To determine the effect of FODMAPs restriction on gut barrier function after dietary intervention among FGID patients
• To determine the effect of FODMAPs restriction on the symptom severity, quality of life and psychological status in FGID patients

This study would be able to provide significant understanding of dietary management of FGID. Conducting this study would provide critical insights into the role of gut microbiota and gut barrier function in the pathophysiology of FGID, highlighting how dietary modulation can impact overall symptom management.

The study design involve screening and recruiting participants, followed by baseline data collection, randomisation, group allocation, and intervention with data collection.

First Visit (Day 1) During baseline, vital information such as socio demographic data will be gathered and FGID screening will be conducted using the ROME III Asian Diagnostic Questionnaire for Adults which consists of the Irritable Bowel Syndrome module and the Gastroduodenal Disorders module. A total of 5 questionnaires will be provide to the participants. These are Irritable Bowel Syndrome Severity Scale (IBS-SSS), Gastrointestinal Symptom Rating Scale (GSRS), Food avoidance and Dietary trigger questionnaire, Hospital Anxiety and Depression Scale (HADS), and the EQ-5D-5L questionnaire.

Body weight and composition of participants will be assessed using the Tanita Body Composition scale, whereas height of participants will be measured using a stadiometer. Dietary and FODMAPs will be estimated using a 4-day food diary (3 weekdays, 1 weekend). Additionally, blood sample will be collected from participants for further assessment. 10 ml blood will be drawn from each participant to detect serum biomarkers. Stool bottle will be provided to participants for stool collection upon the next visit. Stool collection is implemented to assess participants' gut integrity and gut microbiota. After concluding the baseline assessments, patients will be randomised into three groups. Groups A, B and C will follow a restricted FODMAP diet (LFD), Gentle FODMAP diet and traditional dietary advice (TDA), respectively. Participants will be randomly assigned to a study arm by a computer-generated randomisation program using the open-access website www.randomization.com at a ratio of 1:1:1.

Second Visit (Day 8) Participants will return their stool sample and completed diary. The diary will be assessed for completion, and the stool sample will be collected and frozen per protocol. Based on randomisation, participants in the LFD group will be provided with restricted FODMAP advice. In contrast, those in the GFD group will be given general healthy advice by dietitians/researchers trained in delivering the diet. Meanwhile, participants in the TDA group will be given an overall healthy dietary intervention and counselling. All three groups will be advised to follow their respective diets for two weeks. A food diary and another stool collection bottle will be provided.

Phone follow up (Day 15) A phone follow-up is scheduled after a week to remind participants to complete their food diary, answer any doubts or questions relating to their allocated intervention and subsequently plan their next visit.

Final visit (Day 22) Visit 3 will be scheduled after 2 weeks of intervention. Participants will return their stool samples, food diary, and questionnaire. They will also complete two symptom severity questionnaires, food avoidance and dietary trigger questionnaire, with questionnaires to assess quality of life and psychological status and provide a non-fasting blood sample. Additionally, participants in the LFD group will be provided advice on reintroduction. Those who have completed the study will be given an inconvenience allowance.

Inclusion Criteria:

• Aged 18 and above
• Able to provide informed consent
• Those with pre-existing irritable bowel syndrome (IBS) or functional dyspepsia (FD) or both screened by gastroenterologists
• Meet the ROME III- Asian criteria for FGID
• Able to communicate in Malay or English language

Exclusion Criteria:

• Pregnant or lactating women
• History declared by the participant of pre-existing gastrointestinal disorder, including but not limited to Inflammatory Bowel Disease, Coeliac Disease, Pancreatitis, Gallstone disease (biliary colic, cholecystitis), Diverticulitis
• Cancer of any kind
• Patients with reported history of previous resection of any part of the GI tract other than appendix or gall bladder, intestinal stoma
• Habitual use of opiate analgesics likely to alter bowel function e.g. morphine
• Use of antibiotics in the preceding two weeks and/or in the past one month
• Consumption of probiotics, prebiotics or fibre supplements in the past one month
• Enteral feeding or texture modified diet patients
• Those with cognitive impairment or severe mental disorder (Alzheimer's, schizophrenia, bipolar disorder. etc)
• Shift workers (e.g. Nurse, doctors)

We will not be sharing individual patient data to the trial registry to protect participant confidentiality, as institutional policies restrict such disclosure.