This study is to observe the efficacy of the four food elimination diet.

The goals of treatment in EoE, like for most other chronic disorders, include: 1) resolution of clinical symptoms, 2) maintenance of remission and prevention of disease relapse 3) prevention of complications such as fibrosis and strictures by maintaining histological remission 4) prevention of iatrogenic treatment related adverse reactions such as nutritional deficiencies as in dietary treatment and 5) maintenance of quality of life.

Current standard of care for the treatment of EoE include either pharmacologic modality with glucocorticosteroids (oral, or swallowed spray or slurry) or diet. Swallowed steroids are the more commonly utilized form of steroid treatment modality with histological remission rates of 50-80% of subjects. The potential drawbacks of steroid therapy include side effects such as opportunistic infections, potential suppression of the pituitary-adrenal axis with prolonged use and most important disease recurrence once the medication is discontinued.

The dietary approach is based on the hypothesis that food antigen(s) trigger eosinophilic inflammation and clinical and histological remission can be induced by identifying and excluding the causative food antigen(s). It is believed that eliminating causative food antigen(s) target the cause and thus induces long term remission. The current recommendation for treatment of EoE with diet are based on a number of retrospective and observational studies.

This prospective study eliminating the four most common (cow milk protein, wheat, egg, and soy) antigens, will primarily assess the histological response in a cohort of children and will attempt to validate the findings of the previously published retrospective study. In addition by the process of orderly and sequential reintroduction of the excluded solids the investigators will identify the different foods responsible for causing esophageal inflammation and thus disease. This study will also characterize patient demographics, symptoms and histologic changes associated with the four food elimination (4-FED) process.

Health outcomes in children and adolescents related to EoE primarily focus on symptoms and histology. This does not take into consideration the health related quality of life (HRQOL), which may be conceptualized to include physical health, mental health, social functioning, role functioning, and general health perceptions.10 HRQOL has been shown to affect patient satisfaction with and adherence to treatment, and therefore long term outcomes.

The PedsQLTM 4.0 is a, self-administered, non-preference based generic instrument. It consists of a 23-item core measure of global health-related quality of life (HRQOL). The tool includes scales of physical, emotional, social and school function and is validated for children age 2-18 years. Multiple studies have demonstrated the reliability, validity and responsiveness of this instrument in healthy children and in children with chronic diseases. Even more recently developed is the PedsQLTM Eosinophilic Esophagitis Module, a disease-specific tool that has demonstrated excellent feasibility, reliability and validity in EoE patients.

Inclusion criteria:

• Patients ages 12 months-18 years
• Presence of clinical symptoms related to esophageal dysfunction such as: feeding aversion, failure to thrive, vomiting, abdominal pain, dysphagia, heartburn, and food impaction
• Histologic criteria for the diagnosis of EoE with ≥15 eosinophils per high power field from review of a total of six biopsies obtained from the distal and mid (three from each site) esophagus in subjects who were adequately pre-treated with a proton-pump inhibitor- 1mg/kg/dose twice daily, up to a maximum of 40mg or 30mg per dose depending on preparation for 6-8 weeks or had a normal 24 hour ph probe study18
• Patients who agree to 4-FED as their treatment of EoE

Exclusion criteria:

• Those patients who are on oral or swallowed steroids (prior use of steroids that was discontinued more than two months prior to enrollment does not constitute an exclusion criterion)
• Patients who are unable to tolerate the 4-FED
• Patients with concurrent eosinophilic gastroenteritis or eosinophilic colitis

Subjects will be recruited from patients evaluated at, referred to and followed at one of the participating centers. The investigator or designee will recruit participants during clinic visits or over the phone following their diagnosis of EoE and decision of treatment