The Gut Brain Connection

The Gut-Brain Axis: Deep Connections Between the Nervous System and Digestion

By Dr. Cheri King, ND

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Emotions and the Gut: A Historical Understanding

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—bad news, fright, a big test—that elicits a stomach ache, nausea, 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, survived a musket shot to the stomach that never healed, leaving a gaping wound. Dr. Beaumont studied St. Martin and found that when he was irritable, his digestion slowed.

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Hormonal Signaling and the Second Brain

In 1998, Michael Gershon, MD, published The Second Brain, describing serotonin production by gut cells and its role in neurotransmission. Today, it’s widely accepted that the gut and brain are in constant hormonal communication.

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Endobiogeny and the Role of the ANS

Amy Chadwick, ND, introduced Endobiogeny at the 2022 CoAND annual conference. This model sees the endocrine system as the body’s manager, with the autonomic nervous system (ANS) acting as its director. The sympathetic nervous system (SNS) and parasympathetic nervous system (PSNS) work in tandem to regulate digestion.

SNS stimulation:

• Decreases GI motility

• Clamps sphincters

• Reduces enzyme and bile secretion

These are regulated by Alpha 1 and Beta 2 adrenergic receptors and opposed by PSNS stimulation.

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When the Nervous System Disrupts Digestion

Sympathetic dominance:

• Reduces organ blood flow

• Increases histamine (can drive stomach acid and mast cell activation)

For patients with:

• Exocrine pancreatic insufficiency (EPI)

• Gallbladder motility issues

• Reflux:    Consider SNS dominance as a primary factor.

Clinical Case Study 1: SNS Dominance and Gut Dysfunction

A patient presented with severe digestive distress and inability to work. Testing showed near-absent PSNS function. With Vagal Nerve Stimulation (VNS) and nervous system-focused treatment, her symptoms improved dramatically. She regained function and returned to work.

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Clinical Case Study 2: Unexpected PSNS Dominance

A seemingly calm entrepreneur had low testosterone, poor sleep, and elevated heart rate. Testing revealed PSNS dominance, which is GI-related in 80% of cases. He developed digestive symptoms upon treatment but also improved sleep. Later, he experienced excessive sweating and cystic acne—signs of deeper system adjustment. Liver-focused support improved his symptoms.

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Searching for Deeper Mechanisms: Voodoo Death

Research into “Voodoo Death,” a term coined by Walter Cannon in 1942, explains how catecholamine surges can lead to arrhythmia and death. Intracardiac epinephrine can cause massive calcium influx into cardiac cells. The body may compensate with PSNS overdrive, leading to bradycardia and in some cases, death.

This may explain why some stressed patients are PSNS dominant—not as a weakness, but as a compensatory survival mechanism.

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Final Thoughts: Integration and Individualization

The gut-brain axis is complex. Hormonal signaling is just one piece, but a crucial one. Understanding the nervous system’s role in GI health helps us personalize care and interpret patient responses.

Naturopathic Doctors are uniquely trained to identify and treat these interwoven systems—not just to make people feel better, but to help them truly be better from the inside out.

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 Tags: #GutBrainAxis #NaturopathicMedicine #Endobiogeny #NervousSystemBalance #VagalNerve #HolisticHealth