It has been shown that patients complaining of gas-related symptoms significantly improve on a diet low in fermentable residues. However, other studies suggest that some non-absorbable, fermentable meal products (prebiotics) that serve as substrate to colonic bacteria, produce beneficial effects to the host, including improvement of abdominal symptoms. The aim of the study is to compare the effects of a diet low in fermentable residues versus a diet suplemented with prebiotics on intestinal microbiota composition, microbiota activity (intestinal gas production) and digestive symptoms.

Inclusion Criteria:

• Functional digestive disorder with flatulence

• Women and men between the ages of 18 and 80 years (bounds included at the inclusion visit).

• Normal body weight or with overweight (body mass index between 18.0 and 30.0 kg/m2 (bounds included)).

• Women of childbearing potential should be using or complying with one of the medically approved methods of contraception such as, but not exclusively, one of the following:

  1. Birth control pill
  2. Intra-uterine device (IUD)
  3. Double barrier methods (such as condoms and spermicide)
  4. Abstinence

• Willing to follow strict dietary instructions for the duration of the study

• Able to communicate well with the investigator and to comply with the requirements for the study.

Exclusion Criteria:

• Significant illness other than functional bowel disorders
• Disease/disorders which can interfere with the collection of the gas (hemorrhoids,..etc)
• Antecedents of digestive surgery, excluding appendicectomy
• Intake of antibiotics in the month (within 30 days) preceding the inclusion visit.
• Current use of any medications with potential central nervous system effects as judged by the investigator (including but not limited to antidepressants, anxiolytics, opiate pain medications)
• Taking drugs that might modify gastrointestinal function
• Change of dietary habits within the preceding 4 weeks (for instance start of a diet high in fiber) or planned change (For example to start a diet) during the period of the study