When most people think about Parkinson’s disease, they picture tremors, stiffness, and trouble moving. But what if some of the earliest clues—and even potential ways to manage symptoms—were hiding in a completely different part of the body? Research by Columbia University reveals that the gut and the brain are far more connected than we ever realized, and this connection might hold powerful insights for those living with Parkinson’s.
In fact, scientists are now exploring how changes in the gut—such as inflammation or imbalances in gut bacteria—could play a role in the development or worsening of neurological conditions, including Parkinson’s disease. This idea is part of an exciting area of study called the gut-brain axis, and it’s opening up new possibilities for how we think about, prevent, and manage chronic diseases.
So, could your gut be sending signals about your brain health? And more importantly—could supporting your digestive system actually help you feel better and improve your quality of life with Parkinson’s?
Understanding the Gut-Brain Axis
So, what exactly is this “gut-brain connection” we keep hearing about?
Your gut and your brain are in constant conversation. This two-way communication system is known as the gut-brain axis, and it’s made up of nerves, hormones, and even immune signals that travel back and forth between your digestive system and your brain. In fact, your gut has its own nervous system, called the enteric nervous system, which is sometimes referred to as your “second brain.”
One of the major highways for this communication is the vagus nerve, a long nerve that connects the brainstem to various organs, including the stomach and intestines. It sends signals both ways—so what happens in your gut can affect your brain, and vice versa.
But it doesn’t stop there. Your gut is also home to trillions of bacteria—collectively known as the gut microbiome. These microbes play a surprising role in brain health. One of the most important ways they do this is by helping your body produce neurotransmitters.
Neurotransmitters are chemical messengers that carry signals between nerve cells. They help regulate everything from movement and mood to digestion and sleep. In short, they’re essential for the body and brain to work together properly.
Many people are surprised to learn that a large portion of these neurotransmitters are made in the gut—with the help of the microbiome.
Some key neurotransmitters produced in the gut are…
- Serotonin which helps regulate mood, digestion, appetite, and sleep. About 95% of your body’s serotonin is produced in the gut, not the brain. It plays a key role in how we feel emotionally—and how our gut moves physically. It’s often called the “feel-good” chemical.
- Dopamine is known as the “reward” chemical and crucial for motivation, movement, memory, and mood. It’s especially important in Parkinson’s disease, where a drop in dopamine levels leads to many of the condition’s symptoms.
- GABA (gamma-aminobutyric acid) is a calming neurotransmitter that helps regulate anxiety, stress, and mood. Certain gut bacteria help produce GABA, making a healthy gut key to emotional balance.
- Norepinephrine supports alertness, focus, and the body’s stress response. It also helps regulate blood pressure and heart rate. Gut microbes influence how much is produced and how well it’s balanced.
- Acetylcholine supports memory, attention, and muscle control. Some research suggests gut microbiota may influence how this neurotransmitter is regulated, which has implications for both brain and body function.
When the gut is healthy and these neurotransmitters are produced in the right amounts, communication between the gut and brain stays smooth. But when there’s gut dysbiosis—an imbalance of microbes—it can disrupt this chemical messaging system. That can lead to changes in mood, cognition, digestion, and even contribute to neurological conditions like Parkinson’s disease.
Why Gut Health Matters for Parkinson’s
For many people, Parkinson’s disease is seen as a brain disorder—and it is. But what most don’t realize is that the earliest signs of Parkinson’s often show up in the gut.
In fact, studies have shown that digestive symptoms like constipation can appear up to 10 years before the classic motor symptoms, like tremors or stiffness, are diagnosed. Researchers now believe that changes in the gut—specifically, in the balance of bacteria and the health of the gut lining—may play a key role in how Parkinson’s begins and progresses.
So what is going on?
The Gut as a Starting Point
Emerging science suggests that Parkinson’s may actually start in the gut, not the brain. One theory focuses on a protein called alpha-synuclein, which takes on an abnormal shape in Parkinson’s and forms damaging clumps in the brain. Researchers have discovered that this protein can start to become misshaped in the gut and then travel up the vagus nerve to the brain, where it continues to spread and damage nerve cells.
In fact, some animal studies found that cutting the vagus nerve in early stages halted the spread of Parkinson’s, which shows just how important this gut-brain connection may be in the disease process.
Gut Imbalance and Brain Inflammation
Another major factor of the progression of Parkinson’s is gut dysbiosis, or an imbalance of good and bad bacteria in the gut. People with Parkinson’s often have lower levels of bacteria that produce short-chain fatty acids (SCFAs)—natural compounds that help reduce inflammation and protect the gut lining. At the same time, they may have higher levels of harmful bacteria that contribute to leaky gut and systemic inflammation.
When the gut lining becomes “leaky,” toxins and inflammatory compounds can escape into the bloodstream and make their way to the brain. This can trigger neuroinflammation, which may worsen the loss of dopamine-producing brain cells—the hallmark of Parkinson’s.
Put simply: when the gut is inflamed and out of balance, the brain can suffer, too.
For a dive into natural ways to heal leaky gut, check out our blog “Navigating Leaky Gut: Natural Solutions for Restoration and Health.”
Common Signs Your Gut Might Be Affecting Your Brain
If the gut plays such a big role in brain health, especially in Parkinson’s, what should you be looking out for?
Many people are surprised to learn that some of the earliest signs of Parkinson’s aren’t tremors or trouble walking—but digestive issues. These gut-related symptoms often show up years before a formal diagnosis and can be easy to overlook or chalk up to stress, diet, or aging.
Here are some of the most common gut-related symptoms seen in people who later develop Parkinson’s:
- Constipation: One of the most well-known early warning signs. Difficulty having regular bowel movements can indicate slowed gut motility—something linked to changes in the nervous system.
Bloating or gas: Frequent bloating may signal gut bacteria imbalances or slowed digestion, which are common in Parkinson’s. - Indigestion or heartburn: Often caused by poor gut motility or imbalanced stomach acid—both of which may be influenced by gut-brain axis disruption.
- Feeling full too quickly or poor appetite: This could signal slow digestion or loss of normal hunger cues due to nerve changes in the gut.
While these symptoms may seem minor on their own, together they can paint a bigger picture of gut dysfunction that’s affecting the brain.
Early Gut-Brain Warning Signs—Even Before a Diagnosis
Beyond digestion, there are also more subtle or systemic signs that the gut-brain connection is out of balance—often long before any motor symptoms appear:
- Loss of smell or reduced sense of taste: This can occur years before diagnosis and may reflect changes in the nervous system that also affect gut-brain signaling. Since smell and taste are tied to appetite and digestion, these changes are often linked with other gut-related symptoms.
- Unexplained weight loss: May result from poor nutrient absorption or disrupted hunger regulation due to gut inflammation or microbial imbalance.
- Urinary changes or dry mouth: Signs that the autonomic nervous system—which also controls digestion—is being affected. These issues often occur alongside constipation or bloating.
- Increased anxiety or depression: Often tied to imbalances in gut bacteria that affect neurotransmitters like serotonin and GABA. A disrupted gut can lead to more emotional highs and lows or a persistent sense of unease.
- Fatigue or brain fog: When your gut isn’t functioning well, your body may struggle to absorb nutrients or manage inflammation—leading to low energy, poor focus, and mental sluggishness.
- Sleep issues or restless nights: Poor gut health can interfere with the production of melatonin and serotonin—two key hormones for sleep regulation. Gut inflammation may also contribute to light, disrupted sleep or difficulty falling asleep.
Due to the fact that these symptoms often creep in slowly and are easy to brush off, many people don’t realize they could be early signs of deeper imbalances in the gut-brain axis—possibly even years before a Parkinson’s diagnosis.
Functional Medicine’s Approach to Parkinson’s & Gut Health
In functional medicine, the focus isn’t just on treating symptoms—it’s on understanding why those symptoms are happening in the first place. When it comes to Parkinson’s, this means looking deeper into how the gut and brain are communicating, and what might be disrupting that process.
Functional medicine practitioners often start by asking: What’s happening in the gut that could be contributing to inflammation, neurotransmitter imbalances, or even nervous system damage?
Finding Clues in the Gut: The Role of Functional Testing
There are several tools that can help uncover what’s going on beneath the surface—especially in the gut. These tests aren’t about labeling a disease, but rather about finding the imbalances that could be playing a role in how someone feels day to day:
- Gut microbiome testing and stool analysis: These can show whether the gut has an imbalance of harmful vs. helpful bacteria (known as dysbiosis), signs of leaky gut, inflammation, or even infections like H. pylori that may contribute to systemic stress and neuroinflammation.
- Nutrient testing: Identifies deficiencies or excesses in vitamins and minerals critical for nervous system health—like B vitamins, vitamin D, magnesium, and glutathione. These nutrients play a direct role in protecting brain cells and supporting dopamine production.
- SIBO (Small Intestinal Bacterial Overgrowth) breath testing: Because SIBO is common in Parkinson’s and can cause symptoms like bloating, constipation, and fatigue, testing can help determine if gut fermentation is a contributing factor.
Personalized Support for Gut and Brain Health
Once underlying imbalances are identified, functional medicine offers a personalized approach to support gut and neurological health. Here are some of the most commonly used modalities:
- Targeted dietary strategies: Diets rich in anti-inflammatory foods, prebiotics, and resistant starch can feed beneficial gut bacteria and improve the gut lining. In some studies, microbiome shifts have been seen within just a couple of weeks of dietary change.
- Probiotics and prebiotics: Certain strains of probiotics may help restore microbial balance and reduce gut-driven inflammation. Prebiotics help feed those good bacteria so they can thrive.
- Supplementation: Based on test results, supplements might be used to support mitochondrial function (e.g., CoQ10, omega-3s), reduce oxidative stress, and help regulate neurotransmitter production. These are chosen intentionally—not randomly—and are tailored to what the body actually needs.
- Lifestyle adjustments: Movement, stress reduction, and sleep hygiene all support both gut and brain health. Things like walking, gentle stretching, or even meditation can positively impact vagus nerve function and inflammation levels.
Therapies That Support the Gut-Brain Axis
Some clinics, including Michigan Health and Wellness Center, also integrate advanced therapies that aim to reduce inflammation, enhance brain-gut communication, and support the nervous system’s ability to heal. While these are not stand-alone treatments, they may be used alongside nutrition and lifestyle strategies to enhance overall outcomes.
- Cold Laser Therapy (Photobiomodulation): This non-invasive light therapy uses specific wavelengths of light to reduce neuroinflammation and improve cellular energy (ATP) production. For people with Parkinson’s, it may help protect dopamine-producing neurons, calm overactive immune responses, and even support gut healing by reducing inflammation in the digestive tract.
- Hyperbaric Oxygen Therapy (HBOT): By delivering concentrated oxygen in a pressurized environment, HBOT improves oxygen flow to the brain, helping reduce oxidative stress and promote neuronal repair. Research has shown that HBOT may improve motor function, reduce rigidity, and help lower gut and brain inflammation, both of which are linked to the progression of Parkinson’s.
- Theta Chamber Therapy: This therapy combines gentle pulsed electromagnetic fields, sound, and motion to support a parasympathetic state (rest and digest mode). For people with Parkinson’s, it may help improve mood, sleep, and cognitive clarity by calming the nervous system and potentially enhancing vagus nerve tone—which plays a central role in gut-brain signaling.
These therapies may offer meaningful support by helping to lower inflammation, restore balance in the nervous system, and create better conditions for healing in individuals experiencing symptoms of Parkinson’s. Used alongside a root-cause approach to nutrition and lifestyle, they’re part of a more comprehensive strategy for supporting long-term brain and gut health.
Supporting Gut Health to Enhance Neurological Wellness
Parkinson’s disease is complex, and there’s no one-size-fits-all solution—but the growing body of research around the gut-brain connection is offering new hope and direction. What once seemed like a purely neurological condition is now being viewed through a wider, more holistic lens, one that includes the gut, the immune system, and the microbiome.
We now know that digestive symptoms often show up long before a Parkinson’s diagnosis, and that gut imbalances can fuel inflammation, disrupt neurotransmitters, and potentially contribute to disease progression. By supporting gut health through nutrition, lifestyle, targeted testing, and when appropriate, integrative therapies—we can work to create a healthier environment for both the body and the brain.
This approach is not about replacing conventional treatments—it’s about enhancing them by addressing the underlying factors that may be contributing to symptoms. Functional medicine offers a broader view that looks at the connections between gut health, brain health, and the immune system, giving people more tools to support their overall well-being.
If you or a loved one is living with Parkinson’s or beginning to notice signs of gut-brain imbalance, understanding and supporting gut health could be a powerful step forward. Our team at Michigan Health and Wellness is here to help you explore that path. When you’re ready, we invite you to reach out for a personalized consultation and begin your healing journey with support, clarity, and compassion.
Resources
Columbia University Irving Medical Center. (2024). Study adds evidence Parkinson’s starts in the gut. Columbia University. https://www.cuimc.columbia.edu/news/study-adds-evidence-parkinsons-starts-gut
Henry Ford Health. (2025). Gut health and Parkinson’s disease: What’s the connection? https://www.henryford.com/blog/2025/04/gut-health-and-parkinsons-disease
Liu, B., Fang, F., Pedersen, N. L., Tillander, A., Ludvigsson, J. F., Ekbom, A., & Svenningsson, P. (2017). Vagotomy and Parkinson disease: A Swedish register-based matched-cohort study. Neurology, 88(21), 1996–2002. https://www.michaeljfox.org/news/study-vagotomy-may-reduce-parkinsons-risk
Mayer, E. A., Knight, R., Mazmanian, S. K., Cryan, J. F., & Tillisch, K. (2015). Gut microbes and the brain: Paradigm shift in neuroscience. Journal of Clinical Investigation, 125(3), 926–938. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4367209/
Moyer, M. W. (2017). Truncal vagotomy reduces Parkinson disease risk. NEJM Journal Watch. https://www.jwatch.org/na43979/2017/04/26/truncal-vagotomy-reduces-parkinson-disease-risk
Nature Parkinson’s. (2024). The gut-brain axis in Parkinson’s disease: Mechanisms and emerging therapeutic strategies. https://www.nature.com/articles/s41531-024-00681-7
Parkinson’s Foundation. (2024). The gut-brain connection. https://www.parkinson.org/blog/awareness/gut-brain-connection
UCLA Health. (2023). You are what you eat: Diet may affect your mood and brain. https://www.uclahealth.org/news/article/you-are-what-you-eat-diet-may-affect-your-mood-and-brain
