Pre-FIBRe Study: Predeterminants of Fibre Induced Bloating Response.

This study is an exploratory study aimed at gaining a greater understanding of the cause of abdominal bloating in response to two distinct fibre types. This is a single-center, interventional double blinded randomized cross-over study. Each participant will consume each of the study products (placebo, fibre 1 and fibre 2) for a 7-day period with a 3-week washout period in between. Outcomes will be measured before and after each intervention period.

The investigators have 4 hypotheses linked to 4 research questions that will be answered by this research:

Hypothesis 1: participants with self-reported functional bloating in response to either fibre-1 or fibre-2, but not both, will respond symptomatically to fibre-1 or fibre-2, defined as 'fibre-1 responders' and 'fibre-2 responders'.

Hypothesis 2: participants with functional bloating who are 'fibre-1 responders' will be distinguishable from 'fibre-1 non-responders', and 'fibre-2 responders' will be distinguishable from 'fibre-2 non-responders', based upon faecal microbial profiles identified using faecal metagenomics, transcriptomics and metabolites at baseline and following the fibre-1 and fibre-2 interventions.

Hypothesis 3: the microbiota, clinical and nutritional profiles of participants with functional bloating will be interrelated and these relationships will be distinguishable between 'fibre-1 responders', 'fibre-1 non-responders', and 'fibre-2 responders' and 'fibre-2 non-responders'.

Hypothesis 4: participants with visceral hypersensitivity will have different faecal microbiota and will be more likely to be a 'fibre-1 responders' or 'fibre-2 responders' than 'non-responders'.

Participants in the trial will take three different dietary substances, each at a dose of 8 grams per day (split into two serves of 4 gram doses) for 7-days in a double-blinded randomised order with a 3-week washout period in between each intervention. The products are provided in powdered format and will be mixed with water before drinking. The products being provided are glucose, and fibre-1 or fibre-2 (all extracts of commonly consumed food products).

Eligibility Criteria:
Inclusion Criteria:

1. Healthy adults (18-60 years of age inclusive, and BMI 19-29 kg/m2 inclusive) who fulfil criteria for functional bloating as per Rome IV Criteria (to be assessed at screening phone call).
2. Individuals willing to provide consent and follow the protocol
3. Individuals who report that due to perceived trigger food avoidance, symptoms are well controlled i.e. report that over the past 3 days they have had absent or mild bloating on ≥2 days.
4. Individuals that do not fulfil Rome IV criteria for irritable bowel syndrome, functional constipation or functional diarrhoea
5. Individuals that report heightened bloating in response to foods predominantly high in just one type of study fibre i.e not those that report bloating in response to foods high in both. The goal will be to recruit equal proportion of each.
6. Individuals that are not diagnosed with any other chronic gastrointestinal disease or condition including inflammatory bowel disease, coeliac disease.

Exclusion Criteria:

* 1. Excessive habitual intake of fructans, galacto-oligosaccharides, polyols or fructose, as defined by clinician as the sole cause of symptoms.

  2. Individuals with specific diets (eg: strict low-FODMAP). 3. Participation in another clinical trial within the past 4 weeks 4. Subject with known or suspected allergy to any component of the study product(s).

  5. Individuals receiving treatment for anorexia, weight loss, or any form of treatment likely to interfere with metabolism or dietary habits.

  6. Vulnerable subjects defined as individuals whose willingness to volunteer in the clinical trial may be unduly influenced by the expectation, whether justified or not, of benefits associated with participation, or of a retaliatory response from senior members of a hierarchy in case of refusal to participate. (Examples are members of a group with a hierarchical structure linked to the Investigator or to the Sponsor, such as students, subordinate hospital and laboratory personnel, employees of the Investigator or of the Sponsor).

  7. Individuals with antibiotics or proton pump inhibitor (e.g. omeprazole, lansoprazole and esomeprazole, pantoprazole, Rabeprazole) use within the previous 2 months 8. Individuals with current use of medication with potential central nervous system effects as judged by the investigator.

  9. Individuals with previous digestive surgery (except for appendectomy and cholecystectomy performed more than 2 years ago).

  10. Athletes as defined as performing daily strenuous daily exercise for more than 1.5 hours at a time.

  11. Oral disease that may impact on breath sampling e.g. gingivitis, halitosis, oral thrush, candidiasis.

  12. Individuals starting or routinely taking drugs (occasional use is acceptable) that might modify gastrointestinal function such as:
* Prokinetic agents e.g. metoclopramide (Reglan), tegaserod (Zelnorm), domperidone (Motilium),
* Anti-emetics agents
* Corticosteroids
* Narcotic analgesic agents e.g. methadone, fentanyl
* Anticholinergic agents for irritable bowel syndrome
* Medications for constipation e.g. enemas, cathartics, polyethylene glycol solutions, and lactulose.
* 5HT3 antagonists e.g. alosetron and ondansetron.
* Anti-diarrheal agents e.g. Imodium (loperamide)
* Opiate agents used to treat diarrhoea.
* NSAIDs e.g. ibuprofen
* Histamine2 blockers e.g. cimetidine (Tagamet), famotidine (Pepcid), and ranitidine hydrochloride (Zantac), nizatidine (Axid)
* Antacids e.g. Gaviscon, Maalox, Tums, or any that contain magnesium or aluminium
* Supplements used to treat bloating: activated charcoal, alpha galactosidase 13. Women who report they are pregnant/lactating/planning pregnancy 14. Recent/ongoing consumption of probiotics/prebiotic supplements (past 4 weeks) 15. Anticipated changes to consumption of naturally probiotic/prebiotic containing foods e.g. yogurt with live cultures or cereals with chicory etc, in the next 2 months 16. Anticipated changes to smoking habits in the next 2 months 17. Ongoing abuse of alcohol (\>40 units per week)/non-prescription drugs/other medication