Rationale: The dietary short-chain fructooligosaccharides have been shown to increase fecal bacterial mass and fermentation metabolites which might stimulate gut motility. Therefore, these dietary non-digestible carbohydrates might relieve functional constipation.

Objective: Study the effect of short-chain fructooligosaccharides on functional constipation.

Study design: A 16-week, randomized, placebo-controlled, double-blind cross-over trial with intervention periods of 4 weeks with a run-in period of 4 weeks and a wash-out period of 4 weeks.

Study population: Human subjects with functional constipation according to ROMEIII criteria (total n=120; male and female; 18-75 yr).

Intervention: Placebo and one out of 3 dosages of short-chain fructo-oligosaccharides, (Degree of Polymerisation of 3-5; 2, 4 and 8 g/day) for 4 weeks. scFOS will be given as oral chews.

Main study parameters: The primary parameter is the number of complete bowel movements per day in subjects with functional constipation according to Rome III criteria. Secondary outcomes are Stool consistency (Bristol Stool Scale), Stool frequency, Severity of symptoms (Constipation Scoring System; CSS) and Quality of Life (Patient Assessment of Constipation Quality of Life; PAC-QoL).

Inclusion Criteria:

• Age 18-75 yr

• Agree to study design (signed informed consent)

• At least two of the following symptoms ≥25% of the time with criteria fulfilled for the last 3 months with symptom onset at least 6 months prior to inclusion (ROME III criteria for functional constipation):

  • straining, lumpy or hard stool
  • sensation of incomplete evacuation
  • sensation of anorectal obstruction ⁄ blockage
  • use of manual manoeuvres
  • <3 bowel movements per week

• Availability of internet connection

• BMI 20-30

• Male or female

• Willingness to abstain from functional ingredients and such as probiotics, prebiotics and foods containing high amounts of fermentable fibers and laxatives starting 1 month prior to start of the study as well as during the washout period.

Exclusion Criteria:

• Currently participating in another clinical trial
• Drug usage
• Excessive alcohol usage (>4 consumptions/day or >20 consumptions/week)
• Pregnancy or lactating
• Underlying disease of the GI-tract or previous laparotomy, except cholecystectomy and appendectomy
• Use of antibiotics within 1 month prior to inclusion
• Vegetarians
• Weight loss > 5 kg within 1 month prior to inclusion