Sammendrag
Background: Schizophrenia is a severe psychotic disorder that causes considerable suffering. Management of the disease is challenging and it mainly consists of antipsychotic medication and psychosocial interventions. The pathogenesis is not fully understood, but immune-mediated inflammation associated with dysfunction of the gut-brain-axis, intestinal pathology and hypersensitivity to the proteins gluten and casein, have been suggested as important contributors. In some patients with schizophrenia, antibodies to gliadin and casein that are found in gluten and milk respectively, have been detected. It has been suggested that in these individuals, a gluten- and/or casein-free diet may reduce symptoms of the disease. Objective: To review literature that describes gluten- and/or casein-free diet in the treatment of schizophrenia and to discuss the place of this diet in the management of the disease. Method: Systematic literature searches in electronic databases and review of the bibliography of relevant articles. A total of 11 articles were included. Results: The 11 articles are two case reports and nine clinical studies. The case reports describe symptomatic improvement on a low-gluten/gluten-free diet. The clinical studies used gluten-free or gluten- and milk-free diet, were methodologically flawed and gave varying results. However, several of the research groups agree that gluten-free diet may be effective in a subgroup of individuals diagnosed with schizophrenia – possibly those with antibodies against gluten. Only one study tested the effect of diet based on the participants’ antibody status, with the conclusion that a gluten-free diet may seem to reduce symptoms in individuals with positive antibody status. This was, however, an open label pilot study with only two participants. Conclusion: There is not sufficient evidence to use gluten-free and/or casein-free diet in the standard treatment of schizophrenia. However, randomized controlled trials based on antibody status should be conducted to investigate if a selection of individuals with schizophrenia could benefit from this type of diet.