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.