Effect of Prebiotics Versus Low FODMAPs Diet on Intestinal Microbiota and 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