Evaluation of Acacia Gum on Microbiome and Bowel Function in Participants With Chronic Constipation

Inclusion Criteria: * Healthy subjects without clinical diagnosed diseases with relevant effect on the gastrointestinal system or on visceral motility * Constipation defined as an average of 2 - 3 stools per week (which needs to be confirmed during a prospective run-in phase) * At least one of the following criteria: * straining during more than 25% of defecations * lumpy or hard stools (Bristol Stool Form Scale 1 or 2) present more than 25% of defecations * sensation of incomplete evacuation in more than 25% of defecations * sensation of anorectal obstruction/ blockage in more than 25% of defecations * manual manoeuvre to facilitate more than 25% of defecations (such as digital evacuation or support from pelvic floor) * Criteria of constipation for at least the previous 3 months * BMI 18.5 - 30 kg/m2 * Stable body weight (+/- 5%) in the last 3 months (self-reported) * Willing to maintain normal background dietary habits \& physical activity levels throughout the study period * Written consent to participate in the study Exclusion Criteria: * Relevant history or presence of any severe medical disorder, potentially interfering with this study in the investigator's judgement (e.g. mal absorption, food intolerance or allergy, chronic gastro-intestinal diseases (e.g. Morbus Crohn, Colitis Ulcerosa), chronic kidney or liver disease, severe depression, immunological disorders, severe cardiovascular disease, diabetes, acute malignant disease within last 3 years except basal cell carcinoma of the skin) * Prior abdominal surgery which may present a risk for the subject or confound the study results (according to the investigator's opinion) * Currently (or in the last 3 months) suffering from significant stress, anxiety or depression which, in the subjects opinion, interferes with normal daily life (e.g. has the subject missed days of work due to these conditions) and/or which could be responsible for gastrointestinal problems * Exclusively vegan or vegetarian diet (high fiber content) * Regular laxative use at least once per week * Use of hypolipidaemic drugs (e.g. statins, fibrates, resins, ezetimibe, niacin) * Subject under prescription for medication or taking dietary supplements possibly interfering with this study (such as anti-spasmodic, laxatives and anti-diarrheic drugs or other digestive auxiliaries, use of PPIs, bismuth salts and/or H2-antagonists, fibers etc.) within 2 weeks prior to study start or during the study; Stable medication (more than 3 months) for hypertension or thyroid gland is allowed. * Use of pre- and probiotic supplements * Subjects consuming * food or drinks claimed as 'probiotic', or 'prebiotic more than once weekly * food or drinks claimed as 'rich in fiber' (including specific milk products) more than 3 times per week * more than 3 portions of fruits and vegetables (sum) per day * Smoker * Intake of antibiotics in the last 4 weeks * Pregnancy or breastfeeding (also exclude recent pregnancy in the last 3 months). A pregnancy test will be conducted during screening and visits 1 - 3. * Currently or recently (within 3 months of study entry) taking any medication, which in the opinion of the investigator, could interfere with the outcome of the study, e.g. opioids, anti-psychotics