Recent research has revealed the pivotal role that the gut microbiota might play in psychiatric disorders. In anorexia nervosa (AN), the gut microbiota may be involved in pathophysiology as well as in the gastrointestinal (GI) symptoms commonly experienced. This review collates evidence for the potential role of gut microbiota in AN, including modulation of the immune system, the gut-brain axis and GI function. We examined studies comparing gut microbiota in AN with healthy controls as well as those looking at modifications in gut microbiota with nutritional treatment. Changes in energy intake and nutritional composition influence gut microbiota and may play a role in the evolution of the gut microbial picture in AN. Additionally, some evidence indicates that pre-morbid gut microbiota may influence risk of developing AN. There appear to be similarities in gut microbial composition, mechanisms of interaction and GI symptoms experienced in AN and other GI disorders such as inflammatory bowel disease and functional GI disorders. Probiotics and prebiotics have been studied in these disorders showing therapeutic effects of probiotics in some cases. Additionally, some evidence exists for the therapeutic benefits of probiotics in depression and anxiety, commonly seen as co-morbidities in AN. Moreover, preliminary evidence for the use of probiotics in AN has shown positive effects on immune modulation. Based on these findings, we discuss the potential therapeutic role for probiotics in ameliorating symptoms in AN.

Background: Anorexia nervosa and atypical anorexia nervosa require refeeding as a core part of their treatment, and enteral tube nutrition (ETN) may be needed in some individuals either to supplement or replace oral nutrition. This scoping review aimed to explore outcomes associated with phases of ETN, including initial nutrition, transition from enteral nutrition to oral intake, and to overall nutrition; Methods: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for scoping reviews checklist was used. A systematic search was performed using the Ovid and the Web of Science databases, using relevant search terms identifying 37 studies to be included in the review. Quantitative and qualitative data were synthesised and presented; Results: ETN resulted in similar or higher weight gain than oral nutrition. Refeeding syndrome parameters were comparable between ETN and oral nutrition with some indication that prophylactic phosphate supported mitigation of hypophosphataemia. Global psychological parameters related to the eating disorder improved with nutrition; however, there was an indication that weight and shape concerns did not improve during this period. There was a lack of evidence related to transition from ETN to oral intake. Qualitative data indicated meanings attached to the tube, suggesting that additional support may be needed for the transition away from the tube. Furthermore, consideration may be required to support individuals in mitigating trauma related to ETN under restraint; Conclusions: ETN, when required, is a viable alternative to oral intake. Results indicated the need for further research, especially in the transition from ETN to oral intake with regard to strategies of transition and support, and outcomes related to these strategies.