Changes in Intestinal Permeability 4 Hours After Gluten Challenge

Inclusion Criteria for subjects with Celiac Disease: * Biopsy proven celiac disease diagnosed at least 2 years prior to recruitment * Attest to following a gluten free diet to the best of their ability * Quiescent symptoms on a gluten free diet * Negative tissue transglutaminase at time of recruitment (to be collected with baseline blood work) * A prior endoscopy with small bowel biopsies reviewed by a gastrointestinal pathologist revealing healing Inclusion Criteria for subjects with Non-Celiac Gluten Sensitivity: * Meet diagnostic consensus criteria as defined by Ludvigsson et al in "The Oslo definitions for coeliac disease and related terms" * Attest to following a gluten free diet to the best of their ability * Quiescent symptoms on a gluten free diet * Prior negative evaluation for celiac disease (including tissue transglutaminase IgA with total IgA or small bowel biopsies) * If subjects have had a small bowel biopsies revealing increased intraepithelial lymphocytes (IELs), they will be reviewed as a separate subgroup Inclusion Criteria for Normal Subjects: * No gastrointestinal diagnosis (reflux, eosinophilic esophagitis, inflammatory bowel disease, or irritable bowel syndrome) * No gastrointestinal symptoms (diarrhea, abdominal pain, nausea, vomiting, weight loss) * No family history of celiac disease * Will not be required to have a baseline biopsy Exclusion Criteria: * Tobacco use * Symptomatic coronary disease * Active, severe pulmonary disease * Baseline oxy…