The term Disorders of Gut-Brain Interaction (DGBI) has replaced Functional Gastrointestinal Disorders to better reflect the bidirectional relationship between the central nervous system (CNS) and the enteric nervous system (ENS), often referred to as the first and second brain (Drossman, 2016). The ENS operates bidirectionally, meaning the gut influences the brain, and the brain influences the gut through neural, immune, and endocrine pathways (Foster et al., 2017).
Physical examples of DGBIs include irritable bowel syndrome (IBS) and functional dyspepsia (Black et al., 2020). Dysregulation of the gut microbiome refers to an imbalance in the microbial community, leading to dysbiosis, which further exacerbates symptoms (Wei & Singh, 2021). Gut dysbiosis is also linked to various mental disorders through its effects on neurotransmitter regulation, inflammation, and the hypothalamic-pituitary-adrenal (HPA) axis (Cryan & Dinan, 2012). The depletion of beneficial gut bacteria due to factors like antibiotic use further impairs serotonin production, contributing to anxiety and depression (Bastiaanssen et al., 2020).
How Trauma and Chronic Stress Affect the Nervous System
Trauma significantly affects the gut-brain axis, initiating a cycle of mental and physical discomfort. This occurs largely because trauma activates the sympathetic nervous system, triggering a persistent fight, flight, or freeze response that disrupts autonomic balance and impairs the body’s ability to return to a state of calm. The adage Rest and Digest highlights the need for parasympathetic activation for optimal digestion.
IBS may develop in response to trauma, illustrating how psychological stressors trigger gut dysfunction through brain-gut axis dysregulation (Chrousos, 2009). The fluctuating hyperactivity and hypoactivity associated with PTSD are mirrored in shifts in gut motility, where individuals experience alternating bouts of diarrhea (hyperactive motility) and constipation (hypoactive motility). These disruptions contribute to visceral hypersensitivity, increased intestinal permeability, and heightened inflammation over time.
Trauma activates the HPA axis, increasing cortisol levels, which trigger inflammation, disrupt the microbiome, and alter gut permeability—manifesting as IBS or other gastrointestinal issues (Mayer et al., 2021). Increased intestinal permeability allows bacteria, toxins, and undigested food particles to enter the bloodstream, triggering systemic immune responses and inflammation (Korn, 2023; Kelly et al., 2015).
The Connection Between Trauma, Serotonin, and Gut Health
Trauma disrupts gut function, altering serotonin production and signaling. Approximately 95% of the body’s serotonin is synthesized in the gut by intestinal cells, which communicate directly with the CNS through the gut-brain axis (Carabotti et al., 2015). Serotonin dysregulation exacerbates conditions such as anxiety, depression, obsessive-compulsive disorder (OCD), and post-traumatic stress disorder (PTSD).
Physiological Mechanisms in DGBI
DGBIs are not caused by structural abnormalities but by disruptions in motility, visceral hypersensitivity, mucosal immunity, and microbiome dysregulation, all contributing to symptoms lacking an identifiable organic cause (Mayer et al., 2015). Motility disturbances lead to symptoms such as diarrhea, constipation, and abdominal discomfort (Camilleri, 2017). Visceral hypersensitivity increases GI tract sensitivity, resulting in discomfort and inflammation (Drossman, 2016). The mucosal immune system, a critical barrier and defense mechanism, can become abnormally activated in FGIDs, contributing to inflammation and symptom exacerbation (Wei & Singh, 2021). Stress and nutrition play intersecting roles in DGBI development, with poor nutrition often emerging as a byproduct of trauma.
The Role of Short-Chain Fatty Acids in Gut Health
Gut dysbiosis alters short-chain fatty acids (SCFAs), key metabolites produced by the microbiota that maintain gut homeostasis. A decrease in SCFA-producing bacteria, particularly those responsible for butyrate production, reduces SCFA levels, leading to impaired gut function (Parada Venegas et al., 2019). Supplementation with butyric acid has been found to reduce IBS symptoms (Miga-Orczykowska et al., 2024).
Laboratory Tests for Gut Health and DGBI Management
Advances in testing help identify gut microbiota imbalances, intestinal permeability (IP) issues, and FODMAP sensitivity, aiding IBS management. Intestinal permeability (IP) refers to the passage of material from the GI tract through the gut lining into the body (Camilleri, 2019). FODMAPs are short-chain carbohydrates that are poorly absorbed in the small intestine, contributing to digestive discomfort. A low-FODMAP diet eliminates fermentable oligosaccharides (wheat, garlic, onions, legumes), disaccharides (lactose-containing dairy), monosaccharides (excess fructose from honey, apples), and polyols (mushrooms, sugar-free products) (Gibson & Shepherd, 2010).
Tests for IP include Genova’s Intestinal Permeability Assessment, which measures the absorption of two non-metabolized sugar molecules to assess barrier function, and Cyrex Labs Array 2, which evaluates permeability to large molecules that trigger immune inflammation.
Interventions for Disorders of Gut-Brain Interaction
Nutrition for Gut Health
Several evidence-based interventions support gut-brain axis health. Nutritional approaches include glutamine, which supports intestinal cell regeneration and tight junction integrity to restore gut lining and reduce permeability (Kim et al., 2017). Curcumin, a compound found in turmeric, possesses anti-inflammatory and antioxidant properties that modulate the microbiota, reduce oxidative stress, and enhance mucosal healing (Ghosh et al., 2021).
Psychological Interventions for Gut-Brain Health
Psychological interventions, including cognitive-behavioral therapy (CBT) and hypnotherapy, have demonstrated effectiveness in treating gut-related symptoms. CBT helps modify maladaptive thought patterns, reduce stress-related symptom amplification, and improve emotional regulation, leading to decreased visceral hypersensitivity and symptom-related anxiety.
Gut-Directed Hypnotherapy
Hypnotherapy works through a top-down mechanism by inducing a trance state characterized by theta and delta brain wave activity, improving vagal tone, and regulating digestion (Labus et al., 2015). Studies suggest gut-directed hypnotherapy reduces visceral sensitivity, gut inflammation, and microbiome imbalances (Gonsalkorale et al., 2002). For trauma-related gut dysfunction, hypnotherapy helps reframe the connection between traumatic memories and digestive function, promoting healing. Based on state-dependent memory, learning, and behavior (SDMLB), this method suggests that memories encoded in one state of consciousness can be accessed only by returning to a similar state.
Different hypnotherapeutic approaches include solution-focused hypnotherapy for targeted gut-related concerns and Ericksonian hypnotherapy, developed by Ernest Rossi, which explores SDMLB’s role in stress regulation, gene expression, and immune function. Integrating hypnotherapy with CBT, mindfulness, and body-focused exercises such as body scanning and self-palpation provides a comprehensive approach to symptom relief and sustainable health improvements.
Visceral Manipulation for Symptom Relief
I will often refer clients for Visceral Manipulation (I no longer practice it but did for forty-five years) because of the chronic tension and dysfunction that accrues in response to stress, trauma, and pain due to the digestive process. The gentle application of healing hands to the different organs of the digestive tract can help release state-dependent memory, relax the viscera, and initiate a pleasurable and healing response where there may not have been one for many years.
Conclusion: Restoring Balance in the Gut-Brain Axis
Disorders of Gut-Brain Interaction (DGBI) highlight the profound connection between digestive and mental health, with trauma, stress, and dysbiosis driving gut dysfunction. These disruptions affect motility, immune responses, and neurotransmitter production, contributing to conditions like IBS, anxiety, and depression.
Effective treatment goes beyond symptom management to address gut health through nutrition, psychotherapy and counseling, and bodywork interventions. Nutrients like glutamine, curcumin, and butyric acid support gut repair, while CBT and hypnotherapy help regulate stress responses and improve vagal tone. Visceral Manipulation offers a powerful way to release trauma stored in the digestive organs. By restoring balance in the gut-brain axis, integrative approaches promote lasting healing and overall well-being. Laboratory testing provides insight into microbiome imbalances, guiding targeted care.
References
Camilleri, M. (2017). Diagnosis and treatment of small intestinal bacterial overgrowth: A review. JAMA, 318(4), 354–361. https://doi.org/10.1001/jama.2017.9662
Camilleri, M. (2019). The role of intestinal permeability in gastrointestinal disorders and current methods of evaluation. Alimentary Pharmacology & Therapeutics, 50(1), 5–17. https://doi.org/10.1111/apt.15308
Cyrex Laboratories. (n.d.). Array 2: Intestinal Antigenic Permeability Screen. Retrieved from https://www.joincyrex.com/the-cyrex-system/array-2-intestinal-antigenic-permeability-screen
Danese, A., & McEwen, B. S. (2012). Adverse childhood experiences, allostasis, allostatic load, and age-related disease. Physiology & Behavior, 106(1), 29–39. https://doi.org/10.1016/j.physbeh.2011.08.019
Drossman, D. A. (2016). Functional gastrointestinal disorders: History, pathophysiology, clinical features, and Rome IV. Gastroenterology, 150(6), 1262–1279. https://doi.org/10.1053/j.gastro.2016.02.032
Ghosh, S., Banerjee, S., & Sil, P. C. (2021). The beneficial role of curcumin on inflammation, diabetes, and neurodegenerative disease: A recent update. Food and Chemical Toxicology, 153, 112681. https://doi.org/10.1016/j.fct.2021.112681
Gibson, P. R., & Shepherd, S. J. (2010). Evidence-based dietary management of functional gastrointestinal symptoms: The FODMAP approach. Journal of Gastroenterology and Hepatology, 25(2), 252–258. https://doi.org/10.1111/j.1440-1746.2009.06149.x
Kim, M. H., Kim, H., & Kang, S. S. (2017). The role of glutamine in the intestine and its implication in intestinal diseases. International Journal of Molecular Sciences, 18(5), 1051. https://doi.org/10.3390/ijms18051051
Miga-Orczykowska, N., Lemieszek, P., Sajkiewicz, I., & Rudnicka, K. (2024). Exploring the Therapeutic Potential of Sodium Butyrate in Irritable Bowel Syndrome. A Literature Review. Journal of Education, Health and Sport, 68, 55326. https://doi.org/10.12775/JEHS.2024.68.55326
Parada Venegas, D., De la Fuente, M. K., Landskron, G., González, M. J., Quera, R., Dijkstra, G., Harmsen, H. J. M., Faber, K. N., & Hermoso, M. A. (2019). Short chain fatty acids (SCFAs)-mediated gut epithelial and immune regulation and its relevance for inflammatory bowel diseases. Frontiers in Immunology, 10, 277. https://doi.org/10.3389/fimmu.2019.00277
Wei, L., & Singh, R. (2021). Gut microbiota dysbiosis in functional gastrointestinal disorders: Underpinning the symptoms and pathophysiology. Frontiers in Microbiology, 12, 715506. https://doi.org/10.3389/fmicb.2021.715506
She served as a Fulbright scholar on traditional medicine, a Clinical Fellow at Harvard Medical School, and a National Institutes of Health-funded research scientist in mind/body medicine.
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