High-fat diet alters gut-brain communication

Indulging in high-fat diet changes the populations of bacteria residing inside the gut and also alters the signalling to the brain, says a study. The result is that the brain no longer senses signals for fullness which can cause overeating - a leading cause of obesity.

"When we switch the rats to a high-fat diet, it reorganises brain circuits," said Krzysztof Czaja, associate professor at University of Georgia's college of veterinary medicine. The brain is changed by eating unbalanced foods. "It induces inflammation in the brain regions responsible for feeding behaviour. Those reorganised circuits and inflammation may alter satiety signalling," he added.

So what happens to the microbiota in the intestines after a switch to a high-fat diet?

"Suddenly, different nutrients are changing the microenvironment in the gut and some bacteria begin to overpopulate," Czaja said. Some sensitive bacteria begin to die and some populations may even vanish.

"So, introducing a significant change in the gut environment triggers a cascade of events that leads to this population switch," the authors said. These changes can cause inflammation that damages the nerve cells that carry signals from the gut to the brain, resulting in gut-brain miscommunication.

It is not yet known whether this change is permanent or reversible. The research provides new insight into how balance in the intestinal microbiota and gut-brain communication might be disturbed by the introduction of modified foods high in fat and sugar. The findings are to be presented this week at the annual meeting of the Society for the study of Ingestive Behaviour in Denver, Colorado.