Altered Gut Microbiome May Influence Anorexia Nervosa Development

Researchers demonstrate that a severe imbalance in the intestinal ecosystem containing trillions of bacteria and viruses could contribute to the development of anorexia nervosa.

Anorexia nervosa is not only controlled by the changes in the way the brain regulates appetite and body image, but also by the imbalance in the gut bacteria. This is the conclusion of a new study conducted by an international team headed by Danish scientists.

Anorexia nervosa is a complex mental disorder in which the brain’s reward system changes, and leads to extreme behavioral changes. People suffering from anorexia nervosa radically reduce their calorie intake to look thin.

Eating Disorders
Eating disorders involve extreme attitudes and behaviors towards food and weight. It has the highest suicidal mortality rate than other mental illnesses.

Around 1% of all young people develop anorexia nervosa, and in approximately one in five, it becomes a chronic and often life-threatening disease. 9 out of 10 of those diagnosed with anorexia nervosa are females in their teens or early adulthood.

The disease is caused by a complex interaction between various so-called vulnerability genes and environmental influences. However, it now also appears to be a result of a severe imbalance in the intestinal ecosystem of trillions of bacteria and viruses.

Is There a Role for Gut Microbiome in the Complexity of Anorexia Nervosa?

The new study involved 77 Danish girls and young women suffering from anorexia nervosa and 70 healthy individuals of the same gender. The results published in the journal Nature Microbiology suggest that severe changes in the intestinal microbes and corresponding metabolites in the blood may directly affect the development and retention of anorexia nervosa.

To demonstrate this, the researchers transplanted stools from anorexia cases and healthy individuals, respectively, to bacteria-free mice. The mice receiving stools from individuals with anorexia nervosa had trouble gaining weight, and analyses of gene activities in certain parts of their brain revealed changes in various genes regulating appetite.

In addition, the mice that had been given stools from individuals affected with anorexia nervosa showed increased activity of genes regulating fat combustion likely contributing to their lower body weight.

Using DNA technology and advanced bioinformatics analyses, the researchers identified distinct and marked changes in the composition and function of the intestines’ trillions of bacteria and viruses in cases with anorexia nervosa.

Researchers compared the disruptions of the gut microbiome with blood molecules (metabolites) produced by the gut microbiome demonstrating associations between specific changes of the gut bacteria, blood bacterial molecules, and some personality traits such as distorted body image, drive for thinness, and refusal to eat in those affected by anorexia nervosa.

They also discovered that specific gut bacteria in women with anorexia nervosa produce less vitamin B1. A deficiency of B1 may lead to loss of appetite, various intestinal symptoms, anxiety, and isolating social behavior.

Both findings may form the basis of future clinically controlled trials with B1 vitamin supplements and fermented food or probiotics containing various types of lactic acid bacteria.

The next question is whether basic research can lay the foundation for clinically controlled trials exploring if current treatment for anorexia nervosa – involving psychotherapy, family counseling, and attempts to change the patient’s eating and exercise habits – may benefit from additional treatment aimed at normalizing the intestinal microbiome.

Source-Eurekalert