The next time someone tells you to “listen to your gut” it may be wise follow their advice. Thanks to a number of recent studies, scientists have uncovered a fascinating connection between what goes on in the brain and the vast numbers of microorganisms that inhabit the digestive tract. One new study in particular caught the attention of National Public Radio.
University of California Professor of Medicine and Psychiatry Dr. Emeran Mayer spoke with NPR about the work he’s been doing to learn more about the gut-brain connection. He has a theory that gut bacteria help mold brain structure as we age, and thousands of volunteers have agreed to let Mayer perform MRI scans so he can compare brain structure with their internal microbes.
Basically, we all begin life with a unique mix of microbes all our own—receiving them first as we pass through the birth canal, and then from breast milk and other microbes we encounter in our first years. Those microbial fingerprints, believes Mayer after his initial findings, may cause distinctive changes in brain structure and behavior, thus affecting how we think, feel and behave.
Scientists at McMaster University in Ontario have seen similar results in mice, noting that changes in brain chemistry and behavior occur when gut bacteria is altered. For example, when scientists replaced the gut microbes of timid or anxious mice with those of less fearful mice, the timid ones became bolder. Likewise, aggressive mice became calmer when their internal bacteria were modified.
Research shows the gut-brain connection involves the vagus nerve, which extends from the brain stem to the abdomen and is believed to be how our gut microbes “talk” to the brain. Ever get a belly ache when you were feeling anxious or stressed? You can thank your vagus nerve. And here’s something interesting: when a group of researchers in Ireland cut the vagus nerve in test mice, there was evidence the brain no longer responded to changes in the gut.
All of this is just the tip of the iceberg, but experts like Dr. Mayer and others conducting similar research are excited by the possibility that we may be able to positively impact mood and behavior simply by altering our internal bacterial balance. And from there, who knows what other benefits science may one day attribute to our intestinal bacteria?