There is evidence for the use of a diet low in short chain fermentable carbohydrates (low FODMAP diet) in the management of functional gut symptoms, such as abdominal pain and bloating. However, the provision of advice on the low FODMAP diet can be challenging due to limited resources and the need for a dietitian with expertise in the low FODMAP diet. The aim of this study is to assess the feasibility in terms of recruitment and retention in planning a future trial. The purpose of the future trial will be to investigate the clinical and cost effectiveness, as well as the acceptability of different education methods of the low FODMAP diet for the treatment of IBS.

To date, there are no studies on the implementation of the low FOMDAP diet using a mobile app or leaflets in the education of the low FODMAP diet. Therefore, a feasibility study design was chosen in order to obtain key data on recruitment and retention rates at each study group.

A low FODMAP diet includes FODMAP restriction, FODMAP re-introduction and FODMAP personalisation. This study will focus on FODMAP restriction whereby foods high in FODMAPs are avoided for 4 weeks.

Patients with IBS will be recruited from primary and secondary care centres.

STUDY GROUPS

Group 1: 2 x Booklets produced produced by the Department of Nutrition and Dietetic in Guy's & St Thomas' NHS Foundation Trust, and the Diabetes and Nutritional Sciences Division at King's College London. These booklets have been produced by dietitians and are commonly used in clinical practice across the UK. They contain the following information:

Group 2: Patients will be asked to download an application on their mobile phones or tablets. This application has been produced by dietitians from the Department of Nutrition and Dietetic in Guy's & St Thomas' NHS Foundation Trust, and the Diabetes and Nutritional Sciences Division at King's College London.

Group 3:Patients will attend a clinic visit for a one-to-one consultation with a dietitian. As per current clinical practice, the initial visit will last for 1 hour.

PRIMARY OBJECTIVE The primary objective is to estimate recruitment and retention rates of patients with IBS receiving different education delivery methods of the low FODMAP diet.

SAMPLE SIZE As this is a feasibility study, a formal sample size calculation is not appropriate. For such feasibility studies, sample sizes between 24 and 50 have been recommended. Therefore, for this study, a total sample size of 45 was chosen (15 patients per group). Previous work indicates an approximately 12% attrition rate and, therefore, the final sample size will be 50 patients.

ANALYSIS Descriptive statistics such as mean values, standard deviations (SD) for continuous variables, and counts (percentages) and confidence intervals (CI) for categorical variables will be calculated. To assess recruitment and retention rates the following will be recorded: number of people directly contacting the researchers for the study, number of participants pre-screened and screened, number of participants randomised, number of drop-outs.

ETHICS AND REGULATORY APPROVALS The trial will be conducted in compliance with the principles of the Declaration of Helsinki (1996), the principles of Good Clinical Practice. Ethical approval for this study has been granted by an NRES Committee London.

DATA HANDLING

The Chief Investigator will act as custodian for the trial data. The following guidelines will be strictly adhered to:

1. Patient data will be anonymised
2. All trial data will be stored on a password protected computer and limited to authorised study personnel
3. All records and samples will be stored in a secure environment
4. All trial data will be stored in line with the Data Protection Act
5. Data and samples will be securely stored for 5 years after the study has ended and may be used for further in depth analysis
6. Data may be accessed by regulatory authorities for audit purposes

Inclusion Criteria:

1. Men and women aged 18 or over with IBS, functional diarrhoea or functional bloating based on Rome IV criteria who do not have a major medical condition (diabetes, psychiatric or current eating disorders), gastrointestinal disease (e.g. inflammatory bowel disease, coeliac disease) or history of previous GI surgery, except cholecystectomy and haemorrhoidectomy
2. Individuals with no adequate relief of their symptoms at baseline, as well as those with frequency of abdominal pain or discomfort for 1 or more days/week.
3. Individuals with a BMI of 18.5 kgm2 or more.
4. Individuals able to give informed consent
5. Individuals able to understand English
6. Individuals able to read English
7. Individuals with access to Internet
8. Individuals with smartphone with Android or IOS (Apple) software who are able to download apps.

Exclusion Criteria:

1. Females who report to be pregnant or lactating
2. Individuals with constipation predominant IBS (IBS-C) based on the Rome IV criteria
3. Consumption of antibiotics, in the last 4 weeks prior to the study
4. Individuals with additional specific dietary needs (based on the dietitian's judgment)
5. Individuals with multiple food allergies
6. Individuals who have participated in other trials with investigational products within 3 months prior to screening