Effects of Microbiota Imbalance in Anxiety and Eating Disorders: Probiotics as Novel Therapeutic Approaches

Abstract

Anxiety and eating disorders produce a physiological imbalance that triggers alterations in the abundance and composition of gut microbiota. Moreover, the gut–brain axis can be altered by several factors such as diet, lifestyle, infections, and antibiotic treatment. Diet alterations generate gut dysbiosis, which affects immune system responses, inflammation mechanisms, the intestinal permeability, as well as the production of short chain fatty acids and neurotransmitters by gut microbiota, which are essential to the correct function of neurological processes. Recent studies indicated that patients with generalized anxiety or eating disorders (anorexia nervosa, bulimia nervosa, and binge-eating disorders) show a specific profile of gut microbiota, and this imbalance can be partially restored after a single or multi-strain probiotic supplementation. Following the PRISMA methodology, the current review addresses the main microbial signatures observed in patients with generalized anxiety and/or eating disorders as well as the importance of probiotics as a preventive or a therapeutic tool in these pathologies.

Are the Effects of Malnutrition on the Gut Microbiota–Brain Axis the Core Pathologies of Anorexia Nervosa?

“…Many studies have suggested that intestinal microbiota play a crucial role in metabolic function, immunomodulation, and weight regulation in AN [ 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 ]. However, little is known about the exact interaction mechanisms in AN development and maintenance.…”

“…The crucial role of BMI in development, maintenance, and relapse suggest that a somatic factor may play an essential role the pathogenesis of the disease. Data from a large number of studies indicate that the GMB axis is involved in the maintenance of the disease and seems to be the leading candidate as the mediator of the importance of BMI in the pathogenesis [ 76 , 77 , 78 , 79 , 80 , 81 , 82 ]. Based on our present knowledge, it is reasonable to hypothesize that GMB axis disturbances are the core pathologies of AN and that malnutrition-induced alterations in gut microbiota can be an early step in the pathogenesis of AN.…”

“…The intestinal microbiota seem to plays a crucial role in metabolic function, immunomodulation, and weight regulation in AN [ 59 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 ].…”

“…At birth, the gut is mainly colonized with bacteria from the mother, and the environment dominates over host genetics in shaping human gut microbiota [ 84 ]. Diet shapes the composition of gut microbiota [ 59 ], and dietary changes may easily provoke intense gut microbiota shifts [ 76 , 85 ].…”

Analysis of Psychological and Biological Parameters in Patients Affected by Anorexia Nervosa or Obesity

“…In our opinion this is only a secondary aspect. Indeed, obesity and depression share deeper metabolic relationships-linked to alterations in metabolism-in the blood levels of some hormones, including cortisol and insulin, and an increase in inflammatory factors such as cytokines (Hay, 2013;Navarro-Tapia et al, 2021).…”