Feeding Your Brain With Healthy Bacteria

If the old saying, “You are what you eat,” is true, Americans (and their brain function) may be in trouble.

Behavior of Mice Affected by Diet

A study released last week in the journal Neuroscience suggests a relationship between the bacteria we have in our intestines and how our brain functions. In the study, mice fed high-fat and high-sugar diets showed increases in certain types of gut bacteria and a reduction in others, compared with mice fed a normal diet. The mice that consumed the high-sugar diet took longer to develop long-term and short-term memory. They and the mice that were fed high-fat diets struggled with adapting their behavior to face new situations. The study concluded that diets high in fat or sugar seem to alter the composition of the bacteria in our guts, so that signals coming from our intestines cause our brains to perform differently than with normal, healthy diets.

Feeding Our Beneficial Bacteria

“We’ve known for quite some time that any changes to the microbiome, or living organisms, in our gut can have a negative effect on a person’s overall health,” said Coren Menendez, M.D., a Baptist Health Medical Group physician with Baptist Health Primary Care. “But we’re just starting to scratch the surface on how and why these bacteria are so vital to so many different functions of our bodies.”

As an example, she points to how antibiotics, which generally kill both good and bad bacteria, can cause digestive tract side effects like diarrhea, stomach cramps and nausea. But this latest study seems to go further in suggesting that when certain bacteria are reduced, eliminated or increased, chemicals that reach the brain from these organisms have varying effects.

Human Microbiome Project Lends Clues

“Researchers have believed for more than 30 years that bacteria release neurochemicals that cross over the blood-brain barrier and affect the way the brain functions,” said Brad Herskowitz, M.D., a neurologist with Baptist Health Neuroscience Center. “As a result of the Human Microbiome Project, which started in 2008, there’s an emerging, intriguing body of research that seems to indicate that these organisms, living in our bodies, may impact our brains by the chemicals they emit.”

Dr. Herskowitz notes that from early studies in the Human Microbiome Project, researchers have discovered that beneficial bacteria, like those found in probiotics, have decreased anxiety and depression-like behaviors in rodents. But, he says, no clinical trials have been conducted on humans, so it’s too early to draw any real conclusions.

The Future of Neurologic Treatment?

Dr. Menendez notes that there’s definitely a correlation between nutrition and behavior. “People who have poor diets generally act sluggish and depressed, but we don’t understand all the complexity involved,” she said. “Studies like this one and others being conducted may offer some answers, but likely not the whole picture of what is going on between our digestive system and our brain function.”

Nevertheless, she and Dr. Herskowitz believe this finding will likely lead to new ways to treat brain function decline and some behavioral conditions.

“It’s very early in the research stages at this point,” Dr. Herskowitz said. “But what we are discovering stands to change the way we will think about and approach the treatment of brain disorders in the future.”

Dr. Menendez agrees the research is inconclusive at this point, but encourages people to follow the science that has, so far, been proven.

“We do know that eating nutritious foods leads to better health overall,” Dr. Menendez said. “So, if you replace the fat and sugar in your diet with whole fruits, vegetables, whole grains and lean proteins, you may likely see an improvement in your brain function.”

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