Stomach Bacteria Affects The Way Our Minds Work (Or Don’t Work)

By Joelle Renstrom | Updated

GutsYou are what you eat. We all know it’s true to some extent, but if you’re like me, this cliché will always induce an eye-roll. But leave it to science to give credibility to this adage — recent studies indicate that our gut’s microbes directly affect our brains.

UCLA professor Emeran Mayer is currently conducting a study to test the theory that as we grow up, our digestive bacteria may help form our brain structure, which means that gut bacteria would continue to affect our thoughts, feelings, and behaviors throughout adulthood. Mayer is conducting MRI scans on thousands of volunteer subjects, and is comparing their brains to their guts, particularly gastro-intestinal bacteria. He has only analyzed data from 60 of the volunteers, but has already found indications of a connection.

Mayer’s preliminary results indicate that the connections between different regions of subjects’ brains depend on the kind of bacteria most prominent in their guts. Apparently, we all have a particular species of bacteria that rules over our GI processes, and the specific mix of microbes in our bellies affects the development and wiring of our brain circuits. Mayer is quick to point out, though, that that doesn’t mean changes in behavior are necessarily a result of those microbes. Identifying causal connections and teasing out exactly how they work will take additional research, as well as the analysis of data from the rest of the test subjects.

Other researchers are conducting similar studies with mice. In one experiment, scientists took gut bacteria from fearless mice and swapped it for the gut bacteria of anxious mice. The research indicated that the once-anxious mice became braver and more outgoing. The opposite happened when they reversed the experiment — the brave mice became nervous wrecks. The scientists were also able to change the behavior of the mice by altering their gut microbes with a new diet. When they measured the brain chemistry of the mice, they found alterations in the parts of the brain that regulate emotion and mood, as well as an increase in a chemical that facilitates learning and memory.


If further studies confirm this link, the results could be paradigm-shifting, particularly with regard to understanding brain function, as well as improving brain health and treating brain disease. Scientists could begin working on ways to get the gut to help the brain. It seems likely that the vagus nerve, which runs from the stomach to the brain, has something to do with the connection. When the nerve is severed in mice, their brains no longer respond to changes in their gut bacteria.

So, it turns out to be true — the way to someone’s heart (and brain) is through the stomach. It wouldn’t surprise me at all to see probiotic supplements on the shelves in the near future that promote better moods or combat memory loss. Maybe this will make us take our diets more seriously — or at least, think twice about what we shove into our gullets.