Anorexia nervosa and gut microbiome: implications for weight change and novel treatments

ABSTRACT

Introduction

Host–microbiota interactions may be involved in many physical and psychological functions ranging from the digestion of food, maintenance of immune homeostasis, to the regulation of mood and cognition. Microbiome dysbiosis has been consistently described in many diseases. The pathogenesis and weight regulation mechanism in anorexia nervosa (AN) also seem to be implicated in the dynamic bidirectional adjustment of the microbiota-gut-brain axis. This review aims at elucidating this relationship.

Area covered

This review starts with a description of pathogenic gut-brain pathways. Next, we focus on the latest research on the associations between gut microbiota and weight change in the condition of AN. The strategies to alter the intestinal microbiome for the treatment of this disorder are discussed, including dietary, probiotics, prebiotics, synbiotics, and fecal microbiota transplantation.

Expert opinion

Gut microbiome is inextricably linked to AN. It may regulate weight gain in the process of refeeding via the microbiota-gut-brain axis, while the specific mechanism has yet to be clearly established. In the future, a better understanding of gut microbiome could have implications for developing microbiome-based prevention, diagnostics and therapies.

KEYWORDS:

• Anorexia nervosa
• dysbiosis
• fecal microbiota transplantation
• gut-brain axis
• gut microbiota
• microbiome
• prebiotics
• probiotics

Abbreviations

AN: anorexia nervosa

AN-R: anorexia nervosa restricting type

AN-BP: anorexia nervosa binge-eating/purging type

GI: gastrointestinal

CNS: central nervous system

IBS: irritable bowel syndrome

HPA: hypothalamic-pituitary-adrenal

CAR: cortisol awakening response

GF: germ-free

LPS: lipopolysaccharide

ABA: activity-based anorexia

BBB: blood–brain barrier

TNF: tumor necrosis factor

IL: interleukin

FMT: fecal microbiota transplantation

SCFA: short-chain fatty acid

F/B ratio: Firmicutes/Bacteroidetes ratio

Acknowledgments

The authors would like to thank all the staff of the Department of Clinical Psychology, Shanghai Mental Health Center for their support. This article was proofread by Shuxin Cao and Xudong Shen.

Article highlights

• Anorexia nervosa is a debilitating multifactorial condition in which gut microbiome dysbiosis has been observed.

• Gut microbiome may transmit endocrine, vagus nerve and immune signals to the brain via the microbiota-gut-brain axis, thereby contributing to the mechanisms and behaviors typical of anorexia nervosa.

• Gut microbiome may regulate weight change in people with anorexia nervosa, normal weight and obesity.

• Novel treatments targeting microbiome hold great promise for improving outcomes of anorexia nervosa, while more research is necessary.

Declaration of interest

The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or conflict with the subject matter or materials discussed in this manuscript apart from those disclosed.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This paper was funded by Shanghai Clinical Research Center for Mental Health (19MC1911100), Shanghai Municipal Health Commission (2019ZB0201), Shanghai Jiao Tong University (YG2022ZD026) and two hospital-level research projects of Shanghai Mental Health Center (2020-YJ09 and 2020-QH-04).