Once studied as both a cause of and a cure for bacterial infections and bowel disease, gut microbes are now being examined as a potential way to address eating disorders. New studies are exploring the huge potential of these microscopic bugs.

The human gut is the home to trillions of microbes that help us digest food and keep harmful pathogens from taking over. A host of studies in recent years have shown that changes in diet rapidly shift the populations of microbes living in our guts. According to a recent study in the International Journal of Eating Disorders, eating disorders like anorexia nervosa have a definite effect on gut microbes.

UNC eating disorders researcher Cynthia Bulik is spearheading two different studies looking at the microbiome in eating disorders. Funded by the National Institute of Mental Health, the first study is tracking the microbiomes of 100 people with anorexia from the time they’re first admitted to the hospital until they are discharged at a healthier weight.

“(The fact) that the microbiome of anorexia nervosa hadn’t been studied was mind-boggling," said UNC microbiologist Ian Carroll, a co-investigator on the NIMH study. "We will be taking the microbes out of a complex environment and placing them into a much more controlled one to study their functional impact on weight and behavior.”

Partnered with biotech startup uBiome, the second study is gathering microbiome samples from people with anorexia, bulimia, and binge-eating disorder to gain a more comprehensive picture of eating disorders and the microbiome. Bulik and other eating disorder experts hope that these studies will reveal the biology of eating disorders and provide new insights into treatment.

Scientists are examining what they call the gut-brain axis to understand the effect that microbes in the gut can have on the brain. Previous studies have shown that gut microbes can affect weight gain, and the reverse is true when it comes to eating disorders. Cynthia Bulik described how the extremely low-calorie diets of a person suffering from anorexia nervosa decimate the gut microbes. Only few species can survive. A revival happens during refeeding, allowing for a more diverse microbiome. As Bulik explains, “A diverse microbiome is a healthy microbiome.”