Irritable bowel syndrome (IBS) is the most common GI condition with global prevalence ranging between 10-20%. Although the exact cause is not known there are increasing insights concerning the possible multifactorial etiology including low grade inflammation, neuromodulation, dysbiosis, impaired integrity of the intestinal barrier and more.

Currently, it is believed that changes in the microbiota may activate mucosal innate immune responses, resulting in increased epithelial permeability, activated nociceptive sensory pathways, and dysregulation of the enteric nervous system.

Nearly two thirds of patients with IBS perceive their GI symptoms to be food related, hence, food intolerance may be important factor in the pathogenesis. Diet is a part of IBS treatment but adherence, on the one hand, and restriction, on the other, remain a major problem. [Chey WD, Am J Gastroenterol,2016].

Confocal laser endomicroscopy (CLE) is a technique that permits real-time detection and quantification of changes in intestinal tissues and cells, including increases in intraepithelial lymphocytes and fluid extravasation through epithelial leaks.

Based on CLE analysis of IBS patients with a suspected food intolerance, exposure to candidate food antigens caused immediate breaks, increased intervillous spaces, and increased IELs in the intestinal mucosa. These changes are associated with patient responses to exclusion diets. [Fritscher-Ravens A et al, Gastroenterology. 2019, Gastroenterology. 2014] This technic, also efficient according to former studies, is costly and invasive.

The Alcat Test is a lab based immune stimulation test in which a patient's WBC's (white blood cell) are challenged with various substances including foods, additives, colorings, chemicals, medicinal herbs, functional foods, molds and pharmaceutical compounds. The Alcat Test objectively classifies a patient's response to each test substance as reactive, borderline or non-reactive. Based on these classifications, a customized elimination/rotation diet may be designed.

Diet therapies for IBS are becoming an important part of the treatment for patients with IBS [Lenhart A et al, J Neurogastroenterology Motil 2018] There are many types of elimination diets utilized by patients with IBS including personalized diets based upon mediator release testing and IgG (immunoglobulin G) antibody. These diets have the potential for tailor made personal diet but currently have little or no clinical evidence for efficacy.

Diet therapies, like medical therapies for IBS, should be properly evaluated in appropriate designed clinical trials.

It is also important to protect our patients with IBS from potentially ineffective, costly and unsafe intervention.

Inclusion Criteria:

1. Only adults (>18 years of age) meeting the Rome 4 Criteria for IBS D/M/U and who are willing to adhere to diet restrictions, will be eligible for entry into the study.
2. Patients with 'warning symptoms' (e.g., unexplained weight loss, history of GI cancer or inflammatory bowel disease, rectal bleeding etc) will be required to have had a detailed workup to exclude organic pathology prior to enrollment.
3. Participants will be allowed to continue their IBS medications (e.g., fiber, anti-spasmodics, antidepressants, loperamide, etc.) as long as they had been on stable doses for at least 30 days prior to entering the study and agreed not to change medications or dosages during the trial.
4. In addition, patients will be required to have active symptoms at the entry of the study as defined by having an IBSSSS score of >150 (0-500 scale).

Exclusion Criteria:

1. Patients will be excluded if they fulfill ROME 4 IBS C criteria
2. Have an inflammatory bowel disease, celiac or other inflammatory or gut disorder other than IBS.
3. Have active malignancy of any kind
4. If they are not able to eat PO
5. If they are Using NSAIDS more than once per month and within the 4 weeks prior to inclusion
6. If C reactive protein is above 2 times the normal value or if stool Calprotectin is above 200mcg/gr
7. If they had recent antibiotic use (within 1 month). -