Surprising Ways Your Gut Influences Your Brain Health

We often think of the brain as the body’s command center, sending signals to control everything from breathing to movement, however, it’s important to consider just how much information is sent in the other direction, as the brain receives signals from other organs. Studies show that the gut sends more signals to the brain than the brain does to the gut, establishing a fascinating dialogue between the gastrointestinal and central nervous systems that influences mood, appetite, immunity, and overall health. Preventive Medicine physician, Dr. Dan Angerbauer, explores surprising ways your gut communicates with your brain and why this connection is key to mental and physical wellness.

The Gut-Brain Connection

Several communication pathways link the brain and spinal cord to the stomach, intestines, and colon. This connection allows the gut to send messages back to the brain, shaping how we feel and function.

Dr. Angerbauer explains that there are a few different ways that these systems interact, “one is kind of a neural link or connection.” One of the primary communication channels is the vagus nerve, a major nerve that acts as a "bidirectional highway" running from the brain through the neck to the chest and stomach. Dr. Angerbauer clarifies, “You have the vagus nerve…It’s a bidirectional highway, whereby the gut can actually send signals directly back up to the brain.” This pathway is essential in transmitting gut-related messages that can impact stress, anxiety, and even immune function.

Neurotransmitters: The Gut’s Chemical Messengers

Another way the gut influences the brain is through the production of neurotransmitters. While we often associate neurotransmitters like serotonin with the brain, Dr. Angerbauer highlights a lesser-known fact: “A vast majority of the brain's neurotransmitters are actually produced in the gut.” Serotonin, often called the “happy chemical” due to its role in mood regulation, is produced in the gut to an astonishing degree. Dr. Angerbauer notes, “If you had to guess, you know, what percentage of [serotonin] is produced in the gut, most people would maybe guess 10% or 20%. It's actually over 90% of the serotonin is produced in the gut.” This high level of serotonin production within the gut shows just how crucial gut health is to mental wellness. Besides mood, serotonin also plays important roles in sleep, digestion, learning and memory, and more.

Gut Hormones and Appetite Control

In addition to neurotransmitters, the gut produces hormones that communicate with the brain, such as glucagon-like-peptide-1 (GLP-1). Dr. Angerbauer explains. “They are basically a gut hormone that then goes to the brain and affects satiety and appetite.” Widely used anti-diabetic and anti-obesity medications like Ozempic and Wegovy are based on these natural gut hormones, showing the potent effect that gut hormones can have on brain function, influencing our eating habits and weight management.

Microbiome and Brain Health

Beyond hormones and neurotransmitters, the gut microbiome itself plays an important role in supporting brain health. In addition to prebiotics and probiotics,“there’s this whole other thing called postbiotics,” says Dr. Angerbauer. “And that's basically the microbiome taking food or fibers or whatever the substrate is and turning it into some compound that is actually beneficial for the rest of the body.” One such compound is short-chain fatty acids, which are produced when gut bacteria ferment fibers in the diet. “They seem to help maintain the blood-brain barrier,” Dr. Angerbauer shares, emphasizing the role of these compounds in reducing inflammation and protecting brain health.

The Gut’s Role in Immune Defense

Approximately 70% of the immune system resides in the gut, acting as the body’s first line of defense against harmful invaders. Dr. Angerbauer compares this to a "medieval castle," where the immune system is positioned at the border—the gut—to prevent unwanted substances from entering the body. “You can think of this like a medieval castle. Where if you have a land that you're trying to protect, so to speak, you're going to want to put your army, your defense at the border, because that's where the ‘invaders’ are going to come in.” He explains that the gut barrier is only “one cell thick,” which allows it to perform its selective barrier function effectively, but also leaves it vulnerable to disruption.

When harmful substances like lipopolysaccharide (LPS), found on the outer membrane of bacteria such as E. Coli, salmonella, and other gram negative bacteria, cross the gut barrier, it can activate the immune system and increase inflammation. Dr. Angerbauer clarifies, “If that is coming across into the body, that's going to stir up the immune system and cause inflammation.” Chronic inflammation and elevated levels of LPS have been hypothesized as key drivers of Alzheimer’s pathogenesis. However, while inflammation gets a bad rap, Dr. Angerbauer adds that, “Inflammation is just the body's response to repair or to defend itself. And so with almost everything in biology and health, it's always a balance. It's not good or bad. It needs to be in balance.”

Implications for Cognitive Health

Given the multifaceted ways the gut communicates with the brain, it’s no surprise that scientists are increasingly focused on the gut-brain connection as a potential area for preventing and treating cognitive decline. As Dr. Angerbauer notes, “This is a big area of research right now where we're trying to figure out how can we manipulate the gut, the microbiome, to yield a beneficial outcome in either preventing or treating cognitive decline.”

By fostering a healthy gut through diet, lifestyle, and possibly targeted interventions, we may be able to protect the brain against age-related decline and support mental well-being. Simple practices like consuming a fiber-rich diet, incorporating probiotic foods, and managing stress can positively impact the gut-brain axis, offering a promising avenue for enhancing both gut and brain health.

The complex dialogue between the gut and brain reveals just how interconnected our bodily systems are, and that the health of our brains are truly impacted by our overall wellbeing.

To learn more about how your gut influences your brain health, watch our conversation with Dr. Dan Angerbauer in the video above.

By Alicia J. Barber, PhD