High-Fat Diet May Alter Brain, Behavior

If you're thinking about indulging on a Big Mac and some fries, think again. New research says that a high-fat diet may alter your brain and behavior, increasing your risk of depression and other psychiatric disorders.

It has long been known that diets high in fat increase the risk for medical problems, including heart disease and stroke, but now findings published in the journal Biological Psychiatry suggest that they can also affect your behavior. The researchers believe it's due to changes in gut bacteria, or the gut microbiome.

"This paper suggests that high-fat diets impair brain health, in part, by disrupting the symbiotic relationship between humans and the microorganisms that occupy our gastrointestinal tracks," Dr. John Krystal, editor of the journal in which this study was published, said in a statement.

The human microbiome consists of trillions of microorganisms that naturally exist in our bodies, many of which reside in the gastrointestinal tract. These microbiota are essential for normal physiological functioning.

However, according to previous research, changes in the microbiome may make the host more susceptible to illness, such as neuropsychiatric impairment.

In order to better understand this relationship, a team of researchers at Louisiana State University decided to test whether an obesity-related microbiome alters behavior and cognition, even in the absence of obesity.

During the study, non-obese adult mice were given a normal diet, but received a transplant of gut microbiota from donor mice that had been fed either a high-fat diet or control diet. The recipient mice were then evaluated for changes in behavior and cognition.

What they observed was the animals that received the microbiota shaped by a high-fat diet showed multiple disruptions in behavior - including increased anxiety, impaired memory, and repetitive behaviors. What's more, they also exhibited increased intestinal permeability and markers of inflammation. Signs of inflammation in the brain were also evident and may have contributed to the behavioral changes.

While future research is needed to establish a cause-and-effect relationship, these findings provide evidence that diet-induced changes to the gut microbiome are enough to alter brain function even in the absence of obesity.

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