An interventional study of cellulose and Oat fibre in Gastrointestinal Symptoms, sponsored by University of Helsinki. Not yet recruiting at 1 site in Finland. Open to participants aged 18 Years to 65 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-05-14.
Sponsored by University of Helsinki · Not applicable, Interventional, and Prevention
Fibres found in food are mainly carbohydrates that are not broken down or absorbed during human digestion but instead pass to the colon to be fermented by microbes. Gases produced during bacterial fermentation (hydrogen, methane, and carbon dioxide), can cause unpleasant gastrointestinal symptoms in some individuals, such as bloating, flatulence, and stomach pain. Gas production varies between individuals and is influenced by the chemical structure of dietary fibres, the gut microbes' ability to ferment fibre, intestinal pH, and the transit time of intestinal contents. This randomized clinical trial in healthy adults will investigate how individual variations in the microbiome influence the level of gastrointestinal (GI) symptoms induced by different fibre types during short-term exposure.
The objective of this dietary intervention is to examine the effects of different dietary fibre types on gastrointestinal symptoms in apparently healthy adults and to investigate how these effects relate to the composition and functional capacity of the gut microbiota.
The study is designed as a randomized, crossover intervention trial with a total duration of approximately 6 weeks. A 5-day run-in phase is carried out to stabilize baseline dietary patterns and ensure adherence to study procedures. During the intervention, each participant consumes 3 different fibre-rich products, with each product administered for 4 consecutive days (referred to as a "fibre period"). Each fibre period is separated by a 10-day washout period.
Participants (n=28) are apparently healthy adult males and females aged 18-65 years who experience gastrointestinal/ digestive discomfort during or after eating. Individuals without such symptoms are unlikely to exhibit measurable responses, which would limit the ability to address the study's primary research questions.
During the 4-day fibre period, the daily fibre dose provided by the study product is 20 g for women and 25 g for men (corresponding to 2.5 g of fibre per MJ of energy intake, assuming daily energy intake of 8 MJ for women and 10 MJ for men). During the trial, participants consume three structurally different types of dietary fibre: cellulose (poorly fermentable fibre; microcrystalline cellulose), beta-glucan rich fibre (oat bran-based fibre product), and arabinoxylan rich fibre (rye bran-based fibre product). Participants are randomly assigned into one of the six predefined intervention sequences, which represent all possible orders of exposure to the 3 fibre products. Sequence allocation will be generated prior to enrolment, and participants will receive each fibre-rich test product in a randomized order. Participants are instructed to keep the rest of their diet as habitual as possible during the study. Regular use of dietary supplements must be discontinued for the study duration
Participants report their daily GI symptoms as well as perceived stress and mood through a symptom questionnaire using a mobile app. A total of nine GI symptoms are reported (i.e., stomach/ abdominal pain, stomach cramps, bloating, flatulence, borborygmus, nausea, heartburn, discomfort in the upper abdomen/ unpleasant sensation of fullness following eating, a sudden need to defecate), and their severity of symptoms is assessed on a 0-100 VAS scale. Participants report daily the number of bowel movements through the online form, as well as their daily amount of physical activity. In addition, physical activity is assessed using an accelerometer. Dietary intake is assessed by food records (3-day food records during the run-in period and 2-day food records during each fibre period).
Stool samples are used for the analysis of the gut microbiota and metabolome. Additionally, the the effects of different fibre types on metabolic profiles in blood, urine, and stool samples (including SCFAs), as well as on gases in exhaled breath will be analysed.
University of Helsinki is the lead sponsor of 129 studies on the registry; 19 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Exclusion Criteria:
poorly fermentable fibre, "negative control"
Dietary Supplement: cellulose
fibre-rich product from oat bran
Dietary Supplement: Oat fibre
fibre-rich product from rye bran
Dietary Supplement: Rye fibre
Microcrystalline cellulose; daily dose of fibre from the study product 20 g for females and 25 g for males on 4 consecutive days
Oat bran-based fibre product; daily dose of fibre from the study product 20 g for females and 25 g for males on 4 consecutive days
Rye bran-based fibre product; daily dose of fibre from the study product 20 g for females and 25 g for males on 4 consecutive days
Intensity of gastrointestinal symptoms, total score
The composite score of the intensity of individual gastrointestinal symptoms reported on a VAS scale by the participants.
Time frame: 6 weeks Differences between the fibre periods and fibre periods and run-in period will be compared.
Intensity of stomach/ abdominal pain
Intensity of experienced stomach/ abdominal pain reported on a VAS scale from zero (no pain) to 100 (very intense pain) by the participants on daily basis.
Time frame: 6 weeks. Differences between the fibre periods and fibre periods and run-in period will be compared.
Intensity of bloating
Intensity of experienced bloatingreported on a VAS scale from zero (no symptoms) to 100 (very intense symptoms) by the participants on daily basis.
Time frame: 6 weeks. Differences between the fibre periods and fibre periods and run-in period will be compared.
Intensity of stomach cramps
Intensity of experienced stomach cramps reported on a VAS scale from zero (no pain) to 100 (very intense pain) by the participants on daily basis.
Time frame: 6 weeks. Differences between the fibre periods and fibre periods and run-in period will be compared
Intensity of flatulence
Intensity of experienced flatulence reported on a VAS scale from zero (no symptoms) to 100 (very intense symptoms) by the participants on daily basis.
Time frame: 6 weeks. Differences between the fibre periods and fibre periods and run-in period will be compared.
Intensity of borborygmus
Intensity of experienced borborygmus reported on a VAS scale from 0 (no symptoms) to 100 (very intense symptoms) by the participants on daily basis
Time frame: 6 weeks. Differences between the fibre periods and fibre periods and run-in period will be compared.
Intensity of nausea
Intensity of experienced nausea reported on a VAS scale from 0 (no symptoms) to 100 (very intense symptoms) by the participants on daily basis.
Time frame: 6 weeks. Differences between the fibre periods and fibre periods and run-in period will be compared.
Intensity of heartburn
Intensity of experienced heartburn reported on a VAS scale from 0 (no symptoms) to 100 (very intense symptoms) by the participants on daily basis.
Time frame: 6 weeks. Differences between the fibre periods and fibre periods and run-in period will be compared.
Intensity of discomfort in the upper abdomen or unpleasant sensation of fullness following eating
Intensity of experienced discomfort or unpleasant sensation reported on a VAS scale from 0 (no symptoms) to 100 (very intense symptoms) by the participants on daily basis.
Time frame: 6 weeks. Differences between the fibre periods and fibre periods and run-in period will be compared.
Intensity of a sudden need to defecate
Intensity of experienced discomfort or unpleasant sensation reported on a VAS scale from 0 (no symptoms) to 100 (very intense symptoms) by the participants on daily basis.
Time frame: 6 weeks. Differences between the fibre periods and fibre periods and run-in period will be compared.
Composition and function of gut microbiome
Microbiota-related analyses of the collected stool samples are carried out using DNA-based methods
Time frame: 6 weeks. Differences between the fibre periods and fibre periods and run-in period will be compared.
Number of bowel movements
Number of bowel movements reported by participants on daily basis using a mobile app.
Time frame: 6 weeks. Differences between the fibre periods and fibre periods and run-in period will be compared.
Breath gases
Hydrogen and methane measured from exhaled breath samples during run-in and fibre periods.
Time frame: 6 weeks. Differences between the fibre periods and fibre periods and run-in period will be compared.
Fecal and blood SCFA
Analysis of short chain fatty acids (SCFA) from stool and blood samples
Time frame: 6 weeks. Differences between the fibre periods and fibre periods and run-in period will be compared.
Dietary intake
The intake of dietary fibre and nutrients calculated from food records during run-in and fibre periods.
Time frame: 6 weeks. Differences between the fibre periods and fibre periods and run-in period will be compared.
Physical activity
Level of physical activity and inactivity determined using an accelerometer during run-in and fibre periods.
Time frame: 6 weeks. Differences between the fibre periods and fibre periods and run-in period will be compared.
Metabolomics from feces, blood and urine
Targeted/untargeted analysis of fecal, blood and urine metabolome
Time frame: 6 weeks. Differences between the fibre periods and fibre periods and run-in period will be compared.
Plan to share: No — Data sharing in agreement with the EU General Data Protection Regulation
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