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A Simple Guide to the Brain-Gut Connection

Image of A Simple Guide to the Brain-Gut Connection
Image of A Simple Guide to the Brain-Gut Connection

You’ve probably always known to “go with your gut” when making an important decision, but recent research has shown that the relationship between the brain and the gut goes far deeper than just an emotional barometer. You may have seen people swearing that changing your diet can turn around your mental health, or that simply dealing with stress will clear up any digestive issues.

With the brain-gut connection being such a hot topic these days, it can be hard to separate fact from fiction. We’ve created this explainer to help you understand what we actually know about the brain-gut connection—and how you can (or can’t) use that information to relieve any GI symptoms or mental health challenges you’re dealing with.

What is the brain-gut connection?

Obviously the brain is pretty connected to all the parts of our body: It sends signals telling them what needs to be done to keep us going, and they react. When it comes to our digestive tract, the brain sends signals to help make sure it’s prepped for the food that we eat. So, for instance, just thinking about your next meal can get your salivary glands going and stomach acids flowing.

This communication happens using two systems that connect the brain and spinal cord to the rest of our organs and regulate the body’s unconscious actions: the sympathetic nervous system and the parasympathetic nervous system.

The sympathetic nervous system is in charge of regulating the bodily responses that help us in the face of danger—our “fight or flight” responses. The parasympathetic nervous system is in charge of regulating the processes that keep us alive and healthy when we’re safe—sometimes called the “feed and breed” or “rest and digest” functions. The balance of signals coming from each of these systems can affect things like how quickly digestion happens and how readily you absorb nutrients. It also explains why, when you’re feeling frightened or nervous, you feel it in your gut.

But there’s actually one more piece of this nervous system puzzle that has to do with your digestive tract...

What is the “brain” in my gut?

Some scientists have started referring to the gut as the “second brain” and, while there is not literally a wrinkly little brain hanging out somewhere in your abdomen, there are enough nerve cells in the digestive system to compete with the brain in your head. This network of hundreds of millions of neurons lines your entire gastrointestinal tract, and is called the enteric nervous system (ENS).

Part of why the ENS has been getting so much attention lately is because scientists have learned that it doesn’t just receive signals from the brain, but actually communicates information back. Working in partnership with the vast microbiome of bacteria in your gut, the ENS can do everything from moderating what food you crave based on what your system needs to actually shifting your brain chemistry and emotional state.

Your emotional state, in turn, can affect the signals your brain sends back to your gut, potentially causing or aggravating all manner of digestive conditions. When things are going well, it can be a happy collaboration—when they’re going badly, it can be a vicious cycle.

What does this brain-gut connection have to do with mental health?

Scientists are still at the start of understanding exactly how deep the connection is between gut health and brain health, but it’s becoming increasingly clear that, to some degree, a happier gut can lead to a happier you.

For instance, studies have shown that your gut bacteria influences the levels of different neurotransmitters in your body—such as serotonin—which can drastically change your mood. (There’s a reason most drugs for neurological conditions work by adjusting the levels of these same neurotransmitters.)

So, that stands to reason that working to make sure your healthy gut bacteria is going strong (and any bad bacteria is at bay) would help support your mental health as well. Plenty of emerging studies are backing this up, suggesting that taking care of your gut health can do everything from improving your stress resilience to helping ease depression. Additionally, preliminary evidence shows that certain treatments that stimulate the vagus nerve—which is one of the communication routes between the brain and the gut—can help improve treatment outcomes for major psychiatric conditions like depression and PTSD.

This is not to say that if you have a mood or anxiety disorder adjusting your diet will be a magic bullet. On the flip side, an unhealthy gut will not cause your mental health to plummet. But, if you are managing a neurological condition—or just dealing with chronic stress—it’s worth talking to your doctor about whether a little love for your microbiome as part of your treatment plan could potentially improve your treatment outcomes.

For instance, you may consider improving your intake of probiotic food (which have live strains of beneficial bacteria) and prebiotic food (which are full of fiber that makes your gut bacteria happy). Supplementing your diet with omega-3 fatty acids can also potentially help by increasing your gut biome’s diversity. You can achieve many of these changes with a shift in your diet. For instance, one study found that a balanced diet like the Mediterranean diet could help protect against depression.

How can I use this new information to reduce my GI symptoms?

Like we said above, this brain-gut communication goes both ways, meaning mental disorders could aggravate GI symptoms. Just like how a stressful situation can cause butterflies in your stomach, chronic stress could contribute to or aggravate more chronic gut problems.

So, if you’re feeling some acid reflux or a sudden bout of diarrhea, take a step back and ask yourself if you’ve been more stressed than usual lately. Treating your stress could help alleviate the issue.

Moreover, if you deal with any number of chronic gastrointestinal conditions—like gastroesophageal reflux disease (GERD), irritable bowel syndrome (IBS), or inflammatory bowel disease (IBD)—getting some mental support could benefit you. Multiple studies have shown that a combination of psychologically-based treatment and conventional medical treatment leads to greater improvement in digestive symptoms than medicine alone. Talking to a behavioral medicine specialist, which is a psychologist who works with primary care physicians, could provide you some extra relief.

Dr. Jason Reich, licensed gastroenterologist and digestive health expert, adds: “Gastroenterologists often prescribe antidepressants for GI conditions, such as IBS and functional dyspepsia, in lower doses then they are used for depression or anxiety—we’re targeting the neurons that affect the gut in an attempt to moderate the patient’s response to their symptoms.”


There’s still a lot to learn about how the brain-gut connection works, but it’s clear that taking care of one can benefit the other. At the very least, giving your digestive health and mental health a little extra love certainly can’t hurt your overall well-being.


The information provided in this article is not a substitute for professional medical advice, diagnosis, or treatment. You should not rely upon the content provided in this article for specific medical advice. If you have any questions or concerns, please talk to your doctor.