Traditional Dietary Advice Versus Low FODMAP Diet in Postprandial Functional Dyspepsia

Randomised Trial of Traditional Dietary Advice Versus a Low FODMAP Diet in Postprandial Functional Dyspepsia

Functional dyspepsia is common, affecting 7.2% of the global population, and associated with substantial health impairment. Almost 80% of patients with functional dyspepsia report meal-related symptoms and are classified as having the postprandial distress syndrome (PDS) variant. However, studies evaluating dietary modifications in PDS are sparse. The investigators will perform a randomised trial evaluating traditional dietary advice (TDA) vs. a diet low in fermentable fermentable oligo-, di-, mono- saccharides and polyols (low FODMAP diet) in PDS. 70 patients with PDS will be randomly assigned TDA or a low FODMAP diet. The TDA group will be recommended to eat small, regular meals and reduce the intake of caffeine/alcohol/fizzy drinks, fatty/processed/spicy foods, and fibre. The low FODMAP diet group will be advised to exclude fermentable carbohydrates, which are present in wheat-based products, many fruits/vegetables, pulses, beans, dairy, and sweeteners. Questionnaires are to be completed during the 6-week trial, including self-reported adequate relief of dyspeptic symptoms, and the validated Leuven Postprandial Distress Scale (LPDS), Gastrointestinal Symptom Rating Scale, and Nepean Dyspepsia Quality of Life Index. The primary endpoint to define clinical response will be evaluated over weeks 4-6 as >0.5-point reduction in the PDS subscale of the LPDS (calculated as the mean scores for early satiety, postprandial fullness, and upper abdominal bloating).

Recommended to eat smaller, regular meals and reduce the intake of caffeine/alcohol/fizzy drinks, fatty/processed/spicy foods, and fibre

FODMAPs are fermentable carbohydrates that increase intestinal water and gas production that, in those with visceral hypersensitivity, induces gastrointestinal symptoms. The low FODMAP diet therefore excludes fermentable carbohydrates, which are present in wheat-based products, many fruits/vegetables, pulses, beans, dairy, and sweeteners.

Proportion of clinical responders between traditional dietary advice vs. a Low FODMAP diet on the leuven postprandial distress scale (LPDS)

The Leuven Postprandial Distress Scale (LPDS) assesses the severity of 8 upper gastrointestinal symptoms scored from 0 (none) to 4 (very severe). A difference of 0.5 from baseline for the cardinal PDS symptoms (average of first 3 questions) will be used as a cut-off to determine clinical response by comparing average pre-treatment scores with the average score during weeks 4-6.

Self-reported adequate relief of dyspeptic symptoms as a binary answer (yes or no). A responder will be defined if ≥50% adequate relief of dyspeptic symptoms during weeks 4-6

The validated Gastrointestinal Symptom Rating Scale assesses the symptoms of irritable bowel syndrome, depicting problems with satiety, abdominal pain, diarrhoea, constipation and bloating. Higher scores represent greater symptom severity. Change in scores will be compared within- and between- groups.

The Napean Dyspepsia Scale is a validated questionnaire assessing dyspepsia-related quality of life syndrome, with higher scores representing worse quality of life. Change in scores will be compared within- and between- groups

The Hospital Anxiety and Depression Scale is a validated questionnaire assessing mood, with higher scores representing worse mood. Change in scores will be compared within- and between- groups

The validated patient health questionnaire-12 assess extra-intestinal somatic symptoms, with higher scores representing greater somatic symptom severity. Change in scores will be compared within- and between- groups

The Comprehensive Nutritional Assessment Questionnaire assesses macronutrient and micronutrient intake, FODMAPs, fibre, starch, glycaemic index/load. Change in scores will be compared within- and between- groups

Inclusion Criteria: Fulfil Rome IV symptoms criteria for postprandial functional dyspepsia Normal upper gastrointestinal endoscopy within last 3years Online access English literate Exclusion Criteria: Organic gastrointestinal diseases (e.g. inflammatory bowel disease, GI cancer, coeliac disease) Major abdominal surgery (except laparoscopy, appendectomy, cholecystectomy) Documented H.pylori in the last 3 months History of eating disorders Body mass index <20 Current dietary interventions Current use of opioids or anti-inflammatory drugs Severe systemic disease (e.g. cardiac, renal, respiratory) necessitating frequent medical consultations) Pregnant Diabetes mellitus Scleroderma Memory impairment