Functional and metabolic disorders in celiac disease: new implications for nutritional treatment

Celiac disease (CD) is a chronic disease causing the inflammation of the proximal small intestine, in genetically predisposed individuals. This is triggered by the consumption of the gluten protein and the side effects of the disease are mitigated by a lifelong gluten-free diet (GFD) treatment. The predominant consequence of CD is malnutrition due to malabsorption (with diarrhea, weight loss, nutritional deficiencies, and altered blood parameters), especially in patients who do not show strict adherence to GFD treatment. Recent evidence shows that, despite a lifelong GFD, some functional disorders persist, such as compromised gallbladder function and motility, exocrine pancreatic insufficiency, increased gut permeability, small-intestinal bowel overgrowth, nonalcoholic fatty liver disease (NAFLD), lactose intolerance, and milk allergy. These abnormalities may predispose to the occurrence of overweight and obesity even in CD patients. This review focuses on the principal functional and metabolic disorders in both treated and untreated CD, ranging from alterations of the gastrointestinal system to impaired glucose and lipid metabolism and insulin secretion with the aim of providing new implications beyond a GFD, for an ad hoc nutrition treatment in these patients.