Study Links Anorexia Nervosa Symptoms With Bacteria In The Stomach
When it comes to the causes of anorexia nervosa, most of the attention is paid to social and cultural stresses that weigh on people – especially women – to be thin. However new research suggests a root cause of anorexia may not reside in the brain like it was previously thought. It may reside in the gut.
Researchers at the UNC School of Medicine say individuals with anorexia nervosa appear to have notably different microbial communities within their guts compared to healthy individuals without the disorder. They also say some of the psychological symptoms related to the eating disorder may be associated with the bacterial imbalance.
The researchers say their findings, published recently in the journal Psychosomatic Medicine, add to the growing body of evidence pointing to the existence of a so-called “gut-brain axis.” It is increasingly apparent the trillions of bacteria that line the digestive tract play a significant influence numerous aspects of our cognition and may be associated with several mental illnesses including anxiety, depression, and eating disorders.
“Other studies have linked gut bacteria to weight regulation and behavior,” said Ian Carroll, PhD, senior author of the paper and assistant professor of medicine in the UNC Center for Gastrointestinal Biology and Disease. “Since people with anorexia nervosa exhibit extreme weight dysregulation, we decided to study this relationship further.”
Carroll added, “We’re not able to say a gut bacterial imbalance causes the symptoms of anorexia nervosa, including associated symptoms, such as anxiety and depression. But the severe limitation of nutritional intake at the center of anorexia nervosa could change the composition of the gut microbial community. These changes could contribute to the anxiety, depression, and further weight loss of people with the disorder. It’s a vicious cycle, and we want to see if we can help patients avoid or reverse that phenomenon. We want to know if altering their gut microbiota could help them with weight maintenance and mood stabilization over time.”
For the latest study, the researchers collected fecal samples from 16 women with anorexia nervosa after they were admitted into the UNC Center of Excellence for Eating Disorders, and then again after their weight was restored and they were to be discharged from UNC. Then, a graduate student and lead author of the paper, Susan Kleiman, evaluated the composition and diversity of the gut microbiota in each sample.
According to the findings, Kleiman found significant differences between the gut bacteria populations in samples taken at admission and discharge. The samples taken at clinical admission showed fewer types of bacteria. Lower microbiota diversity is overall linked to poorer health. Upon hospital discharge, the samples showed significantly more diversity but was still notably less diverse than that found in samples from 12 healthy individuals analyzed for the study.
The researchers also observed the overall mood of patients improved as microbial communities also improved.
The findings have led the team of researchers to begin tests evaluating the possibility that interventions to improve microbial abundance and diversity could relieve symptoms related to anorexia nervosa in hopes of improving how anorexia is commonly treated.
“Currently available treatments for anorexia nervosa are suboptimal,” Bulik said. “In addition, the process of weight gain and renourishment can be extremely uncomfortable for patients. Often, patients are discharged from the hospital, and within months and sometimes weeks they find themselves losing weight again and facing readmission. If specific alterations in their microbiota could make renourishment less uncomfortable, help patients regulate their weight, and positively affect behavior, then we might see fewer readmissions and more cures.”