Carbohydrate Reduction and Impact on Gastrointestinal System

TRIAL / STUDY OBJECTIVES AND PURPOSE

The trial aims to investigate the effect of a diet low in FODMAPs on colonic morphology as well as in improving symptoms of irritable bowel syndrome (IBS).

This mechanistic information, along with the clinical data, will allow planning of larger, multi-centre studies of the low FODMAP diet in similar patients.

HYPOTHESES

• Patients on a low FODMAP diet for 2 weeks will have a decreased fasting colonic volume measured by Magnetic Resonance Imaging (MRI) compared to participants who have not started the diet.
• Patients with IBS are more likely to report a clinically important improvement in symptoms following the low FODMAP diet (immediate intervention) compared to those on their habitual diet (delayed intervention).

PRIMARY OBJECTIVE • To compare the proportion of IBS patients reporting a clinically important improvement in symptoms following a low FODMAP diet for 2 weeks against IBS patients who are on their habitual diet.

SECONDARY OBJECTIVES

• Determine the difference in fasting colonic volume of IBS patients receiving low FODMAP dietary intervention after 2 weeks compared to those on habitual diet.

TRIAL DESIGN

This will be a pilot single-blind, randomised, controlled trial (RCT). Since some activity will take place on the University of Nottingham this will be a multi-centre study.

All participants will receive advice from a dietitian on the low FODMAP diet. They will be randomised to one of two parallel treatment arms:

• Low FODMAP dietary advice (immediate intervention)
• Habitual diet (control - delayed intervention )

Inclusion criteria

• Aged 18 and above
• Able to give informed consent
• Previous Diagnosis of IBS by medical practitioner
• Meeting ROME III criteria for IBS
• Investigations showing negative tissue transglutaminase (tTG) IgA antibodies
• Full blood count test does not indicate Anaemia

Exclusion criteria

• Inclusion

• Aged 18 and above
• Able to give informed consent
• Previous Diagnosis of IBS by medical practitioner
• Meeting ROME III criteria for IBS
• Investigations showing negative tissue transglutaminase (tTG) IgA antibodies
• Full blood count test does not indicate Anaemia

Exclusion

• Children (<18 years)
• History declared by the candidate of pre-existing gastrointestinal disorder, including but not limited to:

• Inflammatory Bowel Disease
• Coeliac Disease
• Pancreatitis
• Gallstone disease (biliary colic, cholecystitis)
• Diverticulitis
• Cancer of the gastrointestinal tract
• Reported history of previous resection of any part of the gastrointestinal tract other than appendix or gallbladder
• Intestinal stoma
• Limited understanding of English
• Pregnancy declared by the candidate
• Red flag symptoms such as rectal bleeding, family history of bowel or ovarian cancer, a change in bowel habit to looser and/or more frequent stools persisting for more than six weeks in a person aged over 60 years.
• Investigations showing positive tissue transglutaminase (tTG) IgA antibodies
• Anaemia confirmed by full blood count test
• Habitual use of opiate analgesics likely to alter bowel function e.g. morphine
• Use of antibiotics in the preceding four weeks other than for treatment of index infection.
• Any condition where the candidate is likely to require a course of antibiotics in the next 3 months e.g. severe chronic respiratory disease, recurrent urinary tract infection, lower limb ulceration
• Inability to complete the symptom questionnaires e.g. cognitive dysfunction limiting memory and understanding
• Anyone who in the opinion of the investigator is unlikely to be able to comply with the protocol e.g. chaotic lifestyle related to substance abuse
• Dietary practice not compatible with safe implementation of the trial diet e.g.veganism
• Medical reasons for pre-existing controlled diet that cannot be safely randomised e.g. end-stage kidney disease, diabetes
• Participants taking prebiotic/probiotic