Irritable bowel syndrome (IBS) affects around 5% of the general population and remains a daily problem in clinicians' practices, with inconsistent efficacy of treatments despite patients' high expectations. Intestinal hyperpermeability and visceral hypersensitivity are the two major components of IBS, and both can disrupt gastrointestinal function and ultimately impair patients' quality of life.

Glutamine is a non-essential amino acid that regulates numerous metabolic pathways and plays a key role in the intestine as it is the preferred substrate for enterocytes and immune cells. A decrease in intestinal glutamine synthetase has been found in IBS, suggesting its involvement in the intestinal permeability and visceral hypersensitivity observed in patients. Ex vivo, glutamine is capable of restoring the expression of tight junction proteins in IBS-D patients. Furthermore, glutamine supplementation is capable of reducing abdominal pain and restoring intestinal permeability disorders in a sub-group of patients with intestinal permeability disorders (post-infectious IBS-D).

The marine peptides Gabolysat® produced by the Dielen Laboratory have demonstrated their efficacy on intestinal permeability and inflammation in a preclinical model of IBS (Langlois et al. 2023), similar to glutamine supplementation in these animals. The Dielen® Protect product formulated on the basis of the results of this study combines glutamine and Gabolysat® to provide a comfort solution for IBS patients.

Our working hypothesis is that patients suffering from moderate or severe IBS could benefit from oral supplementation with DIELEN Protect to improve the symptoms associated with IBS.

100 patients with IBS (according to Rome IV criteria) will be included in our study.

All patients will test the treatment for 8 weeks (dielen protect or placebo). The efficacy will be compared between the 2 groups before and after the treatments using validated questionnaires. Therefore, all participants will fill questionnaire before and after 8 weeks of treatments : IBS severity (IBS-SSS), quality of life (GIQLI), Anxiety and depression (HAD), GI symptom related anxiety (VSI), stool frequency and consistancy (BSF scale). Microbiota, metabolomic and short chain fatty acid will be analysed before and after the intervention.

Inclusion Criteria:

• Irritable bowel syndrome according to Rome IV criteria
• Aged between 18 and 75 years
• IBS-SSS > 175 at inclusion
• For women of childbearing age, use of effective contraception (progestins or oestroprogestins or intrauterine device or tubal ligation) for 1 month unless postmenopausal (amenorrhoea of at least 12 months or biologically confirmed diagnosis) or woman who has had a hysterectomy or salpingectomy.
• Irritable bowel syndrome treatments that have been stable for more than one month
• Membership of a social security scheme
• Patient has read and understood the information letter and signed the consent form

Exclusion Criteria:

• Taking probiotics, food supplements containing glutamine, anti-inflammatory drugs or antibiotics in the month preceding the study.
• Allergy to fish and glutamine
• Known renal insufficiency (Glomerular Filtration Rate (GFR)<30mL/min/1.73m2), known hepatic insufficiency (Prothrombin Time (PT)<70%) or known cardiac disease.
• History of organic digestive disease (coeliac disease, inflammatory bowel disease, abdominal surgery other than appendectomy or cholecystectomy)
• Pregnant women, women in labour or breastfeeding mothers
• Person deprived of liberty by an administrative or judicial decision or person placed under court protection / sub-guardianship or guardianship
• Patient taking part in another trial / having taken part in another trial within a 4-week period