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).
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
TRIPLE
Enrollment
41
King's College London
London, United Kingdom
Bloating as measured by the Gastrointestinal Symptom Rating Scale (GSRS) (Primary clinical response): end of first intervention period (day 7)
As this is an exploratory study to determine the underlying mechanisms of bloating the investigators have identified a primary and secondary symptom responder definition (those that become bloated in response to the intervention) that will be used to examine and compare the research outcome measures. The primary responder definition is: reporting moderate or severe bloating (a score of 2 or 3) on at least two of the final three days of the fibre-1 or fibre-2 challenge, measured using the Gastrointestinal Symptoms Rating Scale (GSRS), which rates individual gastrointestinal symptoms on a 4-point Likert scale (0-3). The primary responder definition of response will also be measured at the end of the placebo period.
Time frame: Day 7
Bloating as measured by the Gastrointestinal Symptom Rating Scale (GSRS) (Primary clinical response): end of second intervention period (day 35)
As this is an exploratory study to determine the underlying mechanisms of bloating the investigators have identified a primary and secondary symptom responder definition (those that become bloated in response to the intervention) that will be used to examine and compare the research outcome measures. The primary responder definition is: reporting moderate or severe bloating (a score of 2 or 3) on at least two of the final three days of the fibre-1 or fibre-2 challenge, measured using the Gastrointestinal Symptoms Rating Scale (GSRS), which rates individual gastrointestinal symptoms on a 4-point Likert scale (0-3). The primary responder definition of response will also be measured at the end of the placebo period.
Time frame: Day 35
Bloating as measured by the Gastrointestinal Symptom Rating Scale (GSRS) (Primary clinical response): end of third intervention period (day 63)
As this is an exploratory study to determine the underlying mechanisms of bloating the investigators have identified a primary and secondary symptom responder definition (those that become bloated in response to the intervention) that will be used to examine and compare the research outcome measures. The primary responder definition is: reporting moderate or severe bloating (a score of 2 or 3) on at least two of the final three days of the fibre-1 or fibre-2 challenge, measured using the Gastrointestinal Symptoms Rating Scale (GSRS), which rates individual gastrointestinal symptoms on a 4-point Likert scale (0-3). The primary responder definition of response will also be measured at the end of the placebo period.
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Time frame: Day 63
Secondary response measure: Adequate relief of bloating symptoms assessed by the Global Symptom Questionnaire (GSQ) (Secondary clinical response)
As this is an exploratory study to determine the underlying mechanisms of bloating the investigators have identified a primary and secondary clinical symptom responder definition (those that become bloated in response to the intervention) that will be used to examine and compare the research outcome measures. The secondary responder definition is: reporting not having adequate relief of bloating symptoms on at least two of the final three days of the fibre-1 or fibre-2 challenge, measured using the dichotomous Global Symptom Questionnaire (GSQ). The secondary responder definition of response will also be measured at the end of the placebo period.
Time frame: Day 7, day 21, day 28, day 35, day 56, day 63
Clinical profile: Gas-related gastrointestinal symptom profile assessed by the Intestinal Gas Questionnaire (IGQ)
The IGQ is a multi-choice questionnaire that assesses 17 symptoms associated with abdominal gas production using a Likert scale (0-10).
Time frame: Gas-related gastrointestinal symptom profile will be assessed after each intervention period (days 7, 35 and 63) and after each washout period (days 28 and 56) and once at a control timepoint (day 21).
Clinical profile: Gastrointestinal symptom profile assessed by the Gastrointestinal symptom rating scale (GSRS)
The GSRS is a 4-point Likert scale (0-3, absent-severe) assessing 16 gastrointestinal symptoms.
Time frame: Gastrointestinal symptoms profile will be assessed after each intervention period (days 7, 35 and 63) and after each washout period (days 28 and 56) and once at a control timepoint (day 21).
Clinical profile: Stool form and frequency using the Bristol Stool Form Scale (BSFS)
The BSFS is a visual aid to help track stool form, stool form is ranked from type 1-7 and each stool passed will be recorded according to this scale.
Time frame: The BSFS for each stool passed will be recorded in a 7-day diary and will be assessed after each intervention period (days 7, 35 and 63) and after each washout period (days 28 and 56) and once at a control timepoint (day 21).
Clinical profile: Abdominal girth (cms)
Abdominal girth will be recorded daily using a visual guide for where to measure and a metric measuring tape.
Time frame: Abdominal girth will be recorded daily in a 7-day diary and will be assessed after each intervention period (days 7, 35 and 63) and after each washout period (days 28 and 56) and once at a control timepoint (day 21).
Clinical profile: Visceral hypersensitivity - rectal barostat
Visceral hypersensitivity will be measured using a rectal barostat to measure rectal pressure tolerance (mm Hg) and provide a dichotomous hypersensitivity outcome (yes/no).
Time frame: Visceral hypersensitivity will be measured during the first washout period (between day 7 and day 28)
Nutrition profile: Energy and nutrient intake
Energy and nutrient analysis will be recorded in prospective 7-day diaries and assessed using computerised software (Nutritics) based on food composition data from standard United Kingdom (McCance and Widdowson 2016) food composition tables);
Time frame: Energy and nutrient intake will be recorded daily in a 7-day diary and will be assessed after each intervention period (days 7, 35 and 63) and after each washout period (days 28 and 56) and once at a control timepoint (day 21).
Nutrition profile: Fermentable oligo-, di-, mono- saccharide and polyol (FODMAP) intake
Diet diaries will be analysed for FODMAP intake using the Monash University FODMAP calculator.
Time frame: Dietary intake will be recorded daily in a 7-day diary and will be assessed after each intervention period (days 7, 35 and 63) and after each washout period (days 28 and 56) and once at a control timepoint (day 21).
Microbiome profile: Faecal transcriptomics from stool sample (microbiota activity) (metatranscriptomics profiling)
Time frame: Days 21, 28, 35, 56, and 63
Microbiome profile: Faecal Volatile Organic Compounds (VOC) (gas-chromatography mass-spectrometry) from stool sample
Time frame: Days 21, 28, 35, 56, and 63
Microbiome profile: Faecal Short-Chain Fatty Acids (SCFA) (gas-liquid chromatography) from stool sample
Time frame: Days 21, 28, 35, 56, and 63
Microbiome profile: Fermentation (direct breath hydrogen and methane tests) using Gastrogenius breath-gas analyser
Time frame: Days 21, 28, 35, 56, and 63