The Gut Brain Connection

Historically, we know the gut and brain are connected.  We know this not only through scientific literature but also through personal experience.  Most of us have had an emotional event, e.g., bad news, a fright, big tests, etc., that elicits a stomach ache, nausea, anorexia, or diarrhea.  We feel emotions in our gut.

As early as 1822, surgeon Dr. William Beaumont observed that emotions affected digestion.   His patient, Alexis St. Martin, a Canadian Fur Trader, survived a musket shot to the stomach that never healed.  When he ate, food would fall out of the gaping wound.   Dr. Beaumont studied St. Martin (perhaps unethically) and found that when he was irritable, his digestion slowed. 

Researchers sought the gut/brain mechanism for more than a century, but it eluded most until 1998, when Michael Gershon, MD, published his groundbreaking book The Second Brain.  In his book, Gershon describes the discovery that serotonin is made by enterochromaffin cells in the gut and acts as a neurotransmitter and signaler.  It is now widely accepted that the gut and brain constantly communicate through hormonal signaling. 

Amy Chadwick ND took this further, introducing Endobiogeny at the 2022 CoAND annual conference.  Endobiogeny sees the endocrine system as the body’s manager.  The autonomic nervous system (ANS) primarily directs the endocrine system and assists it by regulating the duration and intensity of signaling. 

Beaumont saw this firsthand with St. Martin.  Irritability slowed his digestion.  We now know that stimulation of the sympathetic nervous system (SNS) decreases gastric and intestinal motility.  Sphincters clamp shut, the pancreas decreases enzyme secretion, and the gallbladder relaxes, reducing bile flow.   These processes are inhibited by stimulation of Alpha 1 and Beta 2 adrenergic receptors and agonized by parasympathetic nervous system stimulation (PSNS).  (Michael, Paul – Treating Digestive Disorder from an Endobiogenic Perspective 2021)

Sympathetic dominance also decreases blood flow to internal organs.  It increases histamine, an excitatory neurotransmitter that can contribute to excess stomach acid via H1 receptors in the stomach and mast cell activation.   (Pompili 2010)

For patients with exocrine pancreatic insufficiency (EPI), gallbladder motility issues, and/or reflux, SNS dominance should be at the top of the differential diagnoses.

The importance of ANS balance did not hit home until two things happened.  First, a patient with bloating, belching, anorexia, and what she described as a “rotten” gut that debilitated her so severely that she was unable to work presented to my office.  I suspected she was SNS dominant, recommended Vagal Nerve Stimulation (VNS), and treated her nervous system/gut connection with some success, but she could not be without the remedies for long before symptoms returned.  The remedies merely palliated her, and she needed a way to look at her nervous system balance. 

I purchased a machine that tested SNS/PSNS balance, and her results showed a nearly non-existent PSNS response.  Seeing the data motivated her, and she became ultra-compliant with her Vagal Nerve Stimulation (VNS) exercises and nurtured her nervous system.  In a remarkably short period of time, her digestive symptoms were so much better.  She was back at work and recovered her life, and she had minor regression when off her remedies.

However, not all patients are SNS-dominant.   Occasionally, patients are PSNS dominant. 

One patient in particular was a 45 year old entrepreneur who appeared as mellow as the month of May.  His chief complaint was low testosterone, poor sleep quality and elevated heart rate for hours after he got home from work.  Surprisingly, he was PSNS dominant.  The test result commentary said that 80% of the time, the up-regulation of the PSNS is GI-related.   He reported no GI symptoms.   I treated his nervous system, and surprisingly, he got screaming diarrhea, bloating, and irregular timing of bowel movements but was sleeping better and calming earlier in the evening. 

I treated his GI symptoms and those cleared, but they were exchanged for profuse sweating, where he soaked his shirts even though it was winter.  He also got cystic acne and swollen lymph nodes.  I continued to treat the nervous system but lowered the dose of the remedies and treated the liver more intensely.   He reported great sleep and was calming in the evening faster; though still there, he had less acne. 

I understood the GI symptoms as normalizing the gut and PSNS connection.  However, why he had PSNS up-regulation in the first place was a mystery.    

My research to answer this question led me to Walter Cannon’s 1942 paper called Voodoo Death, discussing the possible mechanism of why people die of nothing other than fright. 

Other researchers built on Cannon’s work and confirmed that catecholamines, hormones like epinephrine or adrenaline, dump into the heart when a sudden shock occurs, creating an “autonomic storm.”  However, in animal studies, adrenalectomy (or removal of the adrenal glands) did not protect from death. 

Intracardiac release of catecholamines (ie release of hormones like epinephrine into the heart) caused a massive calcium influx into cardiac cells, increasing blood pressure and creating tachycardia (high heart rate) and arrhythmias.  The body compensated by increasing Vagal Tone, which created extreme bradycardia (slow heart rate) and, in some cases, death.  Overcompensation of the PSNS led to death. (Hawkins & Clower, 1971)

Voodoo death is the extreme case. However, some patients under long-term stress may not burn out their SNS but instead up-regulate PSNS to compensate. This was likely the case with my patient. The wisdom of the body up-regulated his PSNS to offset chronic stress so he could meet the demands of his life.  He felt fine enough and hand minimal symptoms.  However, all systems must be in homeostasis or balance for long-term health and thriving.

The gut/brain axis is a vast subject, and hormonal signaling is only one aspect, although a crucial one. Understanding the communication between organ systems and how they impact health helps us understand patient symptoms and why they respond to treatments the way they do.  Naturopathic Doctors have the unique education and ability to help patients not only feel better but to actually BE better from the inside out.  And that is the only way we can truly thrive. 

Dr. Cheri King specializes in difficult-to-treat digestive disorders, biotherapeutic drainage, and biological medicine. She sees patients in her Broomfield office and via telemedicine. She teaches gastroenterology at the Colorado School of Clinical Herbalism.