## 3 Results
### Mucosal Alterations and Food Allergy in IBS: Insights from Confocal Laser Endomicroscopy
The 12-week protocol also monitored microbiome changes, but results are pending [43]. Abstracts reported symptomatic improvement in more than 80% of IBS patients with negative IgE serological tests following an unblinded dietary intervention based on CLE results excluding trigger nutrients [44; 45]. The elimination of trigger foods improved symptoms, which worsened upon reintroduction after 4 weeks [46]. A German research group recently published two studies evaluating the effectiveness of CLE in detecting food-induced mucosal alterations. The studies focused on two heterogenous patient populations: one with \"functional abdominal pain\", selected using the Digestive Symptom Frequency Questionnaire (DSFQ) [40], and the other with \"gastrointestinal adverse reactions to food\" (GARF) [41]. The latter study placed greater emphasis on the relationship between symptoms and food, while still utilizing the same standardized symptom assessment tool. [PERSON] and colleagues found that most patients with functional abdominal pain exhibited food-induced mucosal barrier alterations, primarily triggered by soy and wheat [40]. Of these, 67.6% (23/34) showed a positive fluorescein test, indicating barrier dysfunction and 69.5% (16/23) experienced significant pain reduction after an exclusion diet guided by CLE results. Duodenal biopsies following the food challenge test revealed a normal mucosa, with no signs of inflammation, atrophy, or structural abnormalities. Intraepithelial lymphocytes (IELs) and mast cells were within normal ranges. Mast cells showed no anomalies in distribution or morphology, and markers for mast cell dysfunction, such as tryptase and diamine oxidase, were within normal limits. In another study conducted by [PERSON] et al. [41]. CLE was used to study mucosal reactions to foods in 71 patients, all of whom had functional gastrointestinal symptoms, including 52 patients with self-reported gastrointestinal adverse reactions to food (GARF+) and 19 without food-related symptoms (GARF\(-\)). The main symptoms were bloating, abdominal pain, and diarrhea. Patients with positive stimulation tests underwent personalized exclusion diets. Among GARF + patients, 70% showed food-related reactions, primarily to soy, wheat, and milk, with fluorescein leakage into the duodenal lumen. Even 74% of GARF\(-\) patients displayed a local mucosal response with duodenal food challenge. After four weeks of dietary changes, 79% of GARF+ patients experienced significant symptom reduction, compared to 14% of GARF\(-\), with a statistically significant difference between groups (\(p<0.05\)) [41]. Lastly, [PERSON] and colleagues analyzed symptom changes (abdominal pain, bloating, urgency) before and after intraduodenal lipid infusion to stimulate intestinal sensitivity, comparing healthy individuals and IBS patients [42]. A total of 41 individuals were included: 26 IBS patients without organic disease and 15 healthy volunteers. Intestinal permeability was evaluated using CLE and a lactulose/manitol test. Transcriptomic analyses were performed to assess gene expression in Transient Receptor Potential Vanilloid (TRPV) channels. After lipid infusion, no significant differences in intestinal permeability were observed between groups. However, IBS patients reported more severe symptoms, correlated with higher TRPV1 and TRPV3 expression in the duodenum and jejunum. TRPV1 was positively associated with pain and inversely correlated with rectal sensitivity thresholds (r = \(-0.48\), \(p<0.05\)), while TRPV3 was linked to bloating and urgency, with a significant association in female patients [42].