The Importance of Vagus Nerve Health

In the remarkable human body, the vagal nerves, also known as the vagus nerve, act as a conduit, carrying signals between your brain, heart, and digestive system. As the longest nerve in the body, the vagus nerve serves as a switchboard, taking many calls simultaneously while connecting the brain to various organs, including the gut, heart, and lungs. While sending signals in both ways between your gut and brain, the vagus nerve also controls a wide range of involuntary functions, from digestion and breathing to heart rate, the immune system, relaxation, and even reflexes like coughing. Until recently, there has been a crucial gap in direct evidence related to the role of the vagus nerve in gut microbiome and brain communication, but new research confirms that this transmission occurs through the vagus nerve.

Why does this matter? The left and right vagal nerves, which contain 75 percent of the body’s parasympathetic nervous system’s nerve fibers, are an essential part of the body’s nervous system. The parasympathetic nervous system controls “rest and digest” functions and is the opposite of the body’s sympathetic nervous system, which is responsible for the “fight or flight” response. These two nervous systems comprise the autonomic nervous system, which controls involuntary body activities. Proof of the vagus nerve’s significant role in gut microbiome and brain communication emphasizes without question the importance of maintaining a healthy vagus nerve.

Indeed, among the many nerves that make up the nervous system, the vagus nerve stands out for its profound influence on mental and physical health. Likewise, thanks to experts like Dr. Sabine Hazan , people are waking up to the knowledge that the gut microbiome—the microorganisms (or microbes) in the gut, which contain trillions of bacteria, viruses, and fungi—is essential to immunity and overall health. Some bacteria are linked to disease, while others are extremely important to the body’s heart, weight, immune system, and numerous other aspects of health. Amazingly, in total, the gut’s microbes can weigh as much as two to five pounds. This is roughly the same weight as the brain. Wow, and the two communicate via the vagus nerve. The complex yet powerful human body is the coolest thing any of us will ever own.

The recent study proving direct gut-brain communication through the vagus nerve was led by Kelly G. Jameson, a Ph.D. student in the Hsiao Lab at UCLA. Published in February 2025, the researchers observed that mice raised without any gut bacteria, known as germ-free mice, exhibited significantly lower activity in their vagus nerve compared to mice with a normal gut microbiome. Notably, when these germ-free mice were introduced to gut bacteria from normal mice, their vagal nerve activity rose to normal levels. Further experiments introduced antibiotics into the small intestines of normal mice, which led to a decrease in vagal activity. In germ-free mice, antibiotics did not impact vagal activity. However, the vagal activity was restored when the antibiotics were washed out and replaced with intestinal fluids from normal mice. This restoration did not happen with fluids from germ-free mice, emphasizing the integral role of the microbiome in vagal health.

The study also pinpointed specific substances produced by the gut microbiome, such as short-chain fatty acids and bile acids, that stimulate vagal activity through specific receptors. These metabolites triggered different groups of neurons in the vagus nerve, each with its own unique response pattern. This activation spread to neurons in the brainstem, demonstrating a clear pathway for gut-brain communication. The research shows that the gut microbiome regulates specific metabolites that activate the vagus nerve. This activation allows the transmission of chemosensory signals from the gut to the brain. In humans, chemosensory mechanisms are essential for detecting and assessing foods and surely drove the instinctual hunt for nourishment as humanity evolved.

The researchers note that their study improves the understanding of the gut-brain axis and opens up new opportunities for exploring treatments for neurological and gastrointestinal disorders. In other words, make money for Big Pharma. To the large group of us cognizant of the invaluable engine that is the human body, the study instead reinforces the urgent need to take charge of one’s health so the body can effectively communicate internally and heal whatever is ailing. After all, alterations in the gut microbiome influence vagus nerve function—the transmission of signals within the vagus nerve—potentially contributing to conditions like anxiety, depression, and Alzheimer’s. Being unhealthy and depressed is not a good state in which to exist.

What keeps the vagus nerve healthy? For starters, local, small-farm organic animal protein is an excellent choice because it provides amino acids, which are the building blocks for the neurotransmitters that directly influence vagus nerve function and signaling. In other words, help the switchboard run smoothly. For example, choline from animal protein is particularly crucial for producing acetylcholine, a fundamental neurotransmitter associated with vagus nerve signaling.

Guess what is not healthy for the vagus nerve? Sugar. Yes, research shows that excessive sugar consumption negatively influences vagus nerve signaling, mainly by disrupting gut-brain communication via the vagus nerve. This disruption leads to problems with satiety signals (feeling full) and contributes to sugar cravings. Over time, high blood sugar levels directly sabotage the vagus nerve. Like a well-maintained car, when the vagus nerve operates the way God intended, it sends the proper signals about food from the gut to the brain. The body is designed to heal itself when it possesses a healthy mind, body, and spirit fueled by a restorative diet.