Have you ever had a “gut-wrenching” experience? Have you ever experienced “butterflies” or “a pit” in your stomach? Do certain situations leave you “feeling nauseous”? If so, you’re not alone. There is a powerful connection between our gut and brain that is more complex and influential than many people realise.
The gut-brain connection is a powerful communication network between the digestive system (the gut) and the brain, which involves intricate biochemical and neural pathways. Recent research highlights that the health of our gut can significantly influence mental and emotional states, while psychological stress or trauma can directly affect gut function. This relationship is part of what scientists refer to as the gut-brain axis.
The Gut as a “Second Brain”
When we talk about the gut as a “second brain,” we’re referring to a fascinating network of nerves that controls many functions of the digestive system. This network is called the enteric nervous system (ENS), and it operates much like a brain, controlling things like digestion and bowel movements without us having to think about it.
But the ENS doesn’t just control digestion—it also plays a role in how we feel emotionally, with up to 90% of serotonin—a key mood-regulating neurotransmitter—being produced in the gut, indicating a strong connection between gut health and mental well-being.
Here’s how it works:
What is the Enteric Nervous System (ENS)?
The ENS is a complex web of about 100 million nerve cells (neurons) embedded in the walls of the digestive tract, stretching from the oesophagus down to the colon.[1] That’s a huge number of neurons—even more than in the spinal cord. This system of nerves can work independently, which is why it is sometimes called our “second brain.” It doesn’t need instructions from the brain to do its job, though it still communicates with it constantly.
The ENS controls things like:
- How quickly food moves through the digestive system
- The release of digestive enzymes and other chemicals that break down food
- The sensation of “gut feelings” or discomfort when something’s wrong
The Gut-Brain Communication
Even though the ENS can operate independently, it’s in constant communication with the central nervous system (CNS)—which includes your brain and spinal cord—via the vagus nerve, which is explored in much more detail in our blogs on Polyvagal Theory. The vagus nerve is like a two-way highway connecting your brain and gut. When something happens in your gut, the vagus nerve sends signals to your brain, and vice versa. For instance, when you feel stressed or anxious, signals from the brain can cause your stomach to feel upset, leading to butterflies, nausea, or cramps.
Impact of Trauma on The Gut
There is an increasingly documented and researched connection between trauma and stomach or gut issues, both in the long and short term. Research on ACEs (adverse childhood experiences) shows that traumatic or stressful experiences in childhood significantly increase the likelihood of developing stomach and gut health issues later in life.[2] ACEs, such as abuse or domestic dysfunction, lead to chronic stress, which disrupts the gut-brain axis—the communication between the brain and digestive system. This can result in gastrointestinal problems like Irritable Bowel Syndrome (IBS), indigestion, ulcers, and inflammatory bowel diseases.
The connection between ACEs and gut health stems from prolonged stress responses that elevate cortisol and other stress hormones, increasing inflammation and affecting gut health and function. Elevated cortisol levels as a result of chronic stress can alter gut motility, causing diarrhoea or constipation. It also affects the gut microbiome, reducing beneficial bacteria and promoting harmful ones, which can contribute to conditions like irritable bowel syndrome (IBS) and inflammation. Cortisol can increase intestinal permeability, leading to a “leaky gut,” where larger particles pass into the bloodstream, triggering immune responses and inflammation. Additionally, prolonged high cortisol suppresses the gut’s immune defences, making it more susceptible to infections and inflammatory conditions like inflammatory bowel disease (IBD). It can also reduce stomach acid production, impairing digestion and nutrient absorption. Lastly, it can lead to visceral hypersensitivity, making the gut more sensitive to pain or discomfort, as seen in IBS.
Role of Gut Microbiome in Mental Health
The gut microbiome consists of trillions of bacteria, viruses, and fungi living in the digestive system, playing key roles in digestion, immunity, and mental health. These microbes help break down food, support the immune system, and regulate mood by influencing the production of neurotransmitters like serotonin and dopamine.
However, trauma and stress can disturb the balance of these microbes, a condition known as gut dysbiosis. This imbalance can lead to both physical issues like bloating or diarrhoea, and mental health challenges such as anxiety, brain fog, sleep disturbance, depression and more. The gut microbiome also regulates the body’s stress response by modulating cortisol levels. Healthy gut bacteria can help lower cortisol, reducing stress and its associated mental health effects.
Psychosomatic Loop: How Gut Issues Worsen Trauma Responses
The strong connection between the gut and the brain can create a psychosomatic loop, a vicious cycle where gut issues and trauma responses reinforce each other, exacerbating both mental and physical—somatic—health problems. Trauma, particularly from ACEs, elevates cortisol which disrupts gut function. Chronic cortisol exposure weakens the gut lining, causing increased permeability (leaky gut) and allowing harmful particles to enter the bloodstream, triggering inflammation. This inflammation impacts the brain via the gut-brain axis, heightening feelings of stress, anxiety, or depression, further intensifying trauma responses. On top of this, dysbiosis—an imbalance in the gut microbiome caused by stress—reduces beneficial bacteria that help regulate mood.
In turn, gut problems, such as IBS or gluten intolerance can worsen the psychological distress caused by trauma. This gut discomfort sends distress signals to the brain via the vagus nerve, amplifying emotional pain, fear, and anxiety. The continuous feedback between the gut and brain strengthens the psychosomatic loop, where trauma worsens gut issues, and gut issues intensify trauma-related challenges. Breaking this loop often requires interventions that address both gut health and mental health, working with the body to address interconnected issues.
Healing the Gut While Healing From Trauma
Adopting both top-down and bottom-up approaches to target the root cause of psychological and somatic symptoms related to trauma is the best way to achieve real, lasting healing and recovery.
Bottom-up strategies can help clients build bodily awareness, release tension and rebuild a sense of comfort, connection, and safety which are all key to trauma healing. Trauma is rooted in the body, so incorporating body-based approaches alongside more traditional forms of top-down talk therapy is at the core of what we do at Khiron Clinics. Top-down talk therapies use cognitive processing, verbal communication, and present emotional awareness to explore how past experiences and maladaptive behaviour patterns are causing issues and standing in the way of change.
Stomach issues can wreak havoc with our lives, making daily, social activities like eating out, travelling and exercise uncomfortable or distressing, which can further isolate us and worsen mental health struggles. However, there is hope for healing and recovery. Seeing these issues as connected rather than separate offers a road map to recovery through a holistic approach to healing.
Sources:
[1] https://www.hopkinsmedicine.org/health/wellness-and-prevention/the-brain-gut-connection#:~:text=Scientists%20call%20this%20little%20brain,tract%20from%20esophagus%20to%20rectum.
[2] Berens S, Banzhaf P, Baumeister D, Gauss A, Eich W, Schaefert R, Tesarz J. Relationship between adverse childhood experiences and illness anxiety in irritable bowel syndrome – The impact of gender. J Psychosom Res. 2020 Jan;128:109846. doi: 10.1016/j.jpsychores.2019.109846. Epub 2019 Oct 19. PMID: 31759196.
