Intestinal bacteria can cause binge eating and overweight, study says

Certain gut bacteria may increase a person’s risk of binge eating and becoming obese, a new study says.

In a series of experiments, traffic-prone mice and humans had similar levels of two types of bacteria in their microbiomes — one harmful and one beneficial — according to the report presented Thursday at a meeting of the Federation of European Neuroscience Societies and published in the journal Gut.

The researchers also found that by increasing the number of a type of beneficial bacteria called Blautia, they could prevent addictive eating behaviors from developing in the mice.

The new findings are “very important because they show that this type of bacteria protects against the development of compulsive food addiction,” said Elena Martín-García, lead author of the study and associate professor at the Pompeu Fabra University of Barcelona (Spain). .

The team initially analyzed mice and humans to see if there were consistent patterns in the microbiome.

Although food addiction is not considered an official diagnosis, researchers often recognize that some people have trouble controlling their consumption of highly processed foods, such as sweets and snacks.

In future experiments, the team will study whether increasing the Blautia bacteria in humans could help curb traffic jams.

Does the gut talk to the brain?

Researchers aren’t sure how bacteria protect against the development of compulsive eating, but they have theories.

“We speculate that the intestine talks to the brain,” said Martín-García, a researcher at the university’s Neuropharmacology-NeuroPhar Laboratory. “And that can change the function of some brain areas, such as the prefrontal cortex, which is involved in self-control.”

The researchers recruited 88 people, some of whom were addicted to food, along with a collection of 103 mice, including some with compulsive eating habits.

Participants were white women and men from Spain with an average age of 48 years. Thirty-six of the participants were obese; 52 were of normal weight.

It turns out that a certain proportion of mice in the wild develop the urge to binge on food, said Dr. Rafael Maldonado, the study’s other senior author and head of the Neuropharmacology Laboratory—NeuroPhar.

“It is the result of a combination of genetic and environmental factors,” explained Maldonado, professor at Pompeu Fabra University. “Those with a genetic predisposition can lose eating control if they are exposed to unhealthy foods that are obesogenic.”

Obesogenic foods in the human diet are typically high in fat and carbohydrates, such as sugary drinks and desserts and foods containing high amounts of saturated fat and refined carbohydrates, such as pizza, French fries, hamburgers and hot dogs.

Humans and mice with food addiction symptoms had similar patterns of microbiome bacteria that were different from humans and rodents with a healthy relationship with food.

In the next experiment, the researchers exposed a group of mice to “obesogenic” foods that, in addition to being rich in fat and carbohydrates, contained chocolate. About 22% of the mice became compulsive eaters.

“They went crazy for the food,” Martín-García recalled. “They kept hitting the lever asking for more.”

Next, the researchers exposed a group of mice engineered to have higher levels of beneficial bacteria in their gut to the same food. None of them became compulsive eaters.

The next step, Martin-Garcia said, is to boost levels of beneficial bacteria in mice that already have an eating disorder to see if the bacteria can help them eat more normally.

If the result is positive, the group would organize a trial to see if modifying the bacteria in the human microbiome could help reverse the inability to control eating, he explained.

Scientists have come to appreciate more how gut microbes can affect health and behavior, said Dr. Mariana Byndloss, co-director of Vanderbilt’s Center for Microbiome Innovation. “The relationship between the gut and the brain is a very hot topic right now,” Byndloss said.

Although the authors have shown a link between certain bacteria and food sticking, it’s possible that the bacteria aren’t directly causing the problem, said Byndloss, an assistant professor at Vanderbilt University Medical Center.

Low levels of bacteria could be causing problems down the road that lead to addiction issues, or low levels could simply be a marker of compulsive eating.

“There is definitely strong evidence that microbiota contributes to different disease outcomes,” Byndloss said. “But we also know that healthy dietary habits — eating a diet rich in vegetables and complex types of fiber and low in processed foods and saturated fats — promote a healthier microbiome that can protect against chronic disease.”

Previous research has linked bacteria in the microbiome to a variety of diseases, according to Dr. Daniel Wang, a microbiome expert and adjunct professor at Brigham and Women’s Hospital, Harvard Medical School, and the T.H. Chan School of Public Health. On June 25, Wang’s group published research in Nature Medicine linking certain patterns of bacteria in the gut to an increased risk of diabetes.

“This is a very novel and interesting study,” Wang said. “Its main finding, linking the microbiome to food addiction, is an underexplored area.”