A randomized, placebo-controlled, parallel, double-blind trial with three intervention arms and a period of four intervention-weeks that assesses the intake of different dosages of a complex fiber product on bowel function via microbiota changes in subjects that are unsatisfied with their current bowel function.

Background: Bowel function issues can have a substantial effect on quality of life. Additional fiber intake might modulate bowel function and gut microbiota, thereby increasing stool frequency and consistency. This could improve defecation ease, feeling of incomplete bowel emptying and bowel function satisfaction. We hypothesize that a dried vegetable, that is naturally high in fiber within plant cells could improve bowel function in subjects with bowel function issues.

Objective: The main objective of the study is to assess whether a dried multifiber vegetable improves bowel function assessed by stool frequency, consistency, defecation ease, feeling of incomplete bowel emptying and satisfaction. Secondary objectives are to assess whether these effects are dose-dependent and associated with the modulation of the gut microbiota and activity. Furthermore, the adaption of bowel function and adaptation of the gut microbiota and activity over time will be analyzed.

Study design: A parallel, randomized, double-blind, placebo-controlled trial of four weeks with one placebo control and three intervention arms that differ in intervention product dose.

Study population: Healthy human volunteers, 20 - 80y old, with bowel function issues reflected in low stool frequency/consistency, difficulty to defecate, and dissatisfaction with their current bowel function.

Intervention: A vegetable product consisting of dried chicory root cubes containing 85% dietary fiber is added to the daily diet. The intervention product is consumed twice daily for four weeks with a maximum dose of 15 g/day. The control (placebo) consists of easily digestible rice puff particles and is consumed in the same manner as the intervention.

Main study parameters/endpoints: Main study outcome are endpoint (week 4) differences from baseline between the highest dose (15 g/day) of the treatment intervention and placebo in bowel function assessed by changes in stool frequency, stool consistency, ease of defecation, incomplete feeling of bowel emptying and bowel function satisfaction. Secondary endpoints are gut microbiota composition and differences in bowel function, quality of life and constipation symptoms assessment between all doses and placebo. Finally, changes over time in gut microbiota and bowel function will be assessed.

Inclusion Criteria:

• 20 - 80 years old
• Unsatisfied with bowel functions (self-reported), rated on a visual analogue scale (VAS, 0-10) as less than 6
• Four or less bowel movements per week (low stool frequency) and/or
• Hard, lumpy or solid stools (Bristol stool form 1-4) during 90% of bowel movements (hard to solid consistency)
• Able to read and understand Dutch or English

Exclusion Criteria:

• Having a history of medical or surgical events that may significantly affect the study outcome: e.g., IBS or IBD patients and subjects with medically diagnosed constipation (i.e., constipation related to anatomic, medication-related, or readily identifiable physiological causes.)

• Less than one bowel movement per week during the screening

• Medical drug use:

  • Antibiotic use within 3 months of the study screenings day
  • Chronic use of antacids and PPI's
  • Use of laxatives during the screening
  • Chronic use of blood glucose lowering medication

• Consumption of supplements containing fibres (other than laxatives), pro-/ post-/ synbiotics 1 month before the screening

• Not willing to provide faecal samples

• Unable to comply with proper study procedures

• For women of childbearing age: current or planned pregnancy, lactation

• Known allergic reactions to plants from the Asteraceae (Compositae) family (e.g., lettuce, daisies, sunflowers, artichokes, sage, tarragon, chamomile, chicory etc.)

• Reported unexplained weight loss or weight gain of greater than 5 kg in the month prior to pre-study screening

• Reported slimming or medically prescribed diet

• Reported macrobiotic lifestyle

• Personnel the Division of Human Nutrition & Health or the Laboratory of Microbiology

• Current participation in other medical scientific research

• Not having a general practitioner

• Not willing to be informed about accidental discoveries in relation to the subjects health

As the data contains sensitive personal information researchers interested in the data can contact the principal investigator.

Subjects not receiving the intervention product will consume a placebo (rice puff particles). Neither the investigator, nor the participants, nor the outcome assessor will know who received what. No Care Provider is included in this trial.