Eosinophilic esophagitis (EoE) is a unique form of non-immunoglobulin E-mediated food allergy, restricted to the esophagus, characterized by esophageal eosinophil-predominant inflammation and dysfunction. The diagnosis requires an esophago-gastroduodenoscopy with esophageal biopsies demonstrating active eosinophilic inflammation with 15 or more eosinophils/high-power field, following the exclusion of alternative causes of eosinophilia. Food allergens trigger the disease, withdairy/milk, wheat/gluten, egg, soy/legumes, and seafood the most common. Therapeutic strategies comprise dietary restrictions, proton pump inhibitors, topical corticosteroids, biologic agents, and esophageal dilation when strictures are present. However, avoidance of trigger foods remains the only option targeting the cause, and not the effect, of the disease. Because EoE relapses when treatment is withdrawn, dietary therapy offers a long-term, drug-free alternative to patients who wish to remain off drugs and still be in remission. There are currently multiple dietary management strategies to choose from, each having its specific efficacy, advantages, and disadvantages that both clinicians and patients should acknowledge. In addition, dietary regimens should be tailored around each individual patient to increase the chance of tolerability and long-term adherence. In general, liquid elemental diets devoid of antigens and elimination diets restricting causative foods are valuable options. Designing diets on the basis of food allergy skin tests results is not reliable and should be avoided. This review summarizes the most recent knowledge regarding the clinical use of dietary measures in EoE. We discussed endpoints, rationale, advantages and disadvantages, and tailoring of diets, as well as currently available dietary regimens for EoE.

Eosinophilic esophagitis (EoE) is a chronic esophageal disease that needs lifelong management and follow-up. The diagnosis requires an upper endoscopy with at least one esophageal biopsy demonstrating >15 eosinophils/high-power field, and often occurs with a diagnostic delay of up to ten years, partly due to the absence of valid non-invasive screening tools. In addition, serial upper endoscopies with esophageal biopsies are mandatory to assess the efficacy of any ongoing treatment in patients with EoE. These procedures are invasive, costly, and, when performed without sedation, are often poorly tolerated by patients. Therefore, there is the clinical need to identify reliable non-invasive or minimally invasive biomarkers that could be used to assess disease activity in clinical practice as a surrogate of peak eosinophil counts on esophageal biopsies. This review summarizes evidence on investigational non-invasive or minimally invasive biomarkers for the diagnosis and follow-up of EoE to report on the state of the art in the field and support future research. We discussed eosinophil-derived mediators including eosinophil cationic protein (ECP), eosinophil-derived neurotoxin (EDN, also known as eosinophil protein X), eosinophil peroxidase (EPO), and major basic protein (MBP) as well as other promising non-eosinophil-derived biomarkers. Although several studies have shown the utility of most biomarkers collected from the serum, esophageal luminal secretions, and feces of EoE patients, numerous limitations currently hamper the integration of such biomarkers in clinical practice. Future studies should aim at validating the utility of non-invasive and minimally invasive biomarkers using rigorous protocols and updated consensus criteria for EoE.