Enteric Nervous System

The three branches of the autonomic nervous system are the 1) sympathetic, which helps us activate and survive, the 2) parasympathetic, which supports digestion and recovery, and the 3) enteric nervous system (ENS) which thoroughly manages our gut function. Let’s explore the fascinating world of the ENS, its intricate connections to the brain, and how we can care for this vital system to optimize our health.

WHAT IS THE ENTERIC NERVOUS SYSTEM?

The enteric nervous system (ENS) is a complex network of neurons (nerve cells) and supporting cells embedded in the walls of your digestive tract. It contains between 200 and 600 million neurons, with at least 20 specialized types. That’s more nerve cells than in the spinal cord! Often referred to as the “second brain” or “the brain of the gut,” the ENS can operate independently of the brain and spinal cord. However, it still communicates closely with the central nervous system (CNS) via the vagus nerve.

THE ENS’S MAIN TASKS

Regulating Digestion:

The ENS controls gut motility, including processes like the Migrating Motor Complex (MMC), which acts as the gut’s “housekeeping” mechanism, clearing debris and bacteria between meals, preventing stagnation and overgrowth.

It also coordinates the release of digestive enzymes and optimizes nutrient absorption by regulating blood flow to the intestines.

Protecting the Gut:

The ENS helps maintain the integrity of the intestinal lining, preventing leaky gut and supporting the balance of the microbiome.

It works closely with immune tissues like Gut-Associated Lymphoid Tissue (GALT) and Mucosa-Associated Lymphoid Tissue (MALT). These tissues guard the gut against pathogens (invaders) while maintaining a healthy balance with beneficial bacteria.

THE GUT-BRAIN CONNECTION

How The Vagus Nerve Links the ENS & Brain

The vagus nerve acts as the main highway connecting the ENS in the gut to the central nervous system (CNS) in the brain. Handling approximately 80% of the sensory information traveling from the gut to the brain, it’s a critical player in this two-way communication.

Gut-to-Brain Signals:

• The ENS sends sensory information about the gut’s condition—like fullness, inflammation, or microbial activity—up to the brain.

• These signals can influence our mood, cognition, and even decision-making by interacting with brain regions like the hypothalamus (stress regulation) and prefrontal cortex (emotional processing).

Brain-to-Gut Signals:

• The brain also sends commands down the vagus nerve to the ENS, influencing gut motility, secretion of digestive enzymes, and even the release of hormones like ghrelin (hunger) and motilin (MMC activation).

The ENS, Brain, & Mood Regulation

The vagus nerve helps regulate the release neurotransmitters like serotonin and dopamine which are key to emotional well-being. Since ~90% of the body’s serotonin is produced in the gut, disruptions in gut health are linked to mood disorders like anxiety or depression.

A dramatic example of this gut-mood interplay can occur in unmanaged Celiac disease, whereby either an autoimmune cascade in response to gluten or simply malabsorption of key nutrients due to chronic inflammation can lead to psychiatric symptoms, including psychosis.

The Microbiome’s Role

Gut bacteria are critical players in the gut-brain connection, working closely with the ENS and the vagus nerve to influence both gut and brain health.

• Metabolite Production: Gut microbes produce short-chain fatty acids (SCFAs), neurotransmitters like GABA, and other metabolites that can cross the gut barrier and signal to the brain via the vagus nerve.

• Microbial Balance: An imbalance (dysbiosis) in gut bacteria can disrupt vagus nerve signaling, leading to more inflammation or mental health issues like anxiety or brain fog.

Stress’s Impact on the ENS

Chronic Stress: Stress increases the release of cortisol and adrenaline, which disrupt vagus nerve communication and reduce ENS efficiency. This can lead to:

• Slower gut motility or erratic peristalsis, contributing to conditions like IBS.

• Leaky gut, where the intestinal barrier weakens, allowing harmful substances to enter the bloodstream.

Feedback Loop: Stress impairs the ENS, disrupting signals to the brain and amplifying feelings of stress and anxiety in a vicious cycle. This can even drive some people toward compulsive or binge behaviors in an unconscious attempt to soothe their stressed nervous system.

HOW THE ENS IMPACTS YOUR WHOLE BODY

Mental Health

It really is amazing how interconnected our gut health and our mood are. And there are so many idioms in our language that have pointed to this all along: “Trust your gut.” Having “a fire in your belly.” Being so worried your “guts are in knots.” Having “butterflies in our stomach” when we like someone or are nervous. These expressions reflect the very real connection between our gut and emotions.

When our gut is dysregulated, it impacts our ability to make neurotransmitters, which impacts mood and even our ability to make decisions. Because our gut isn’t composed of just our cells, it’s also home to 100 trillion microorganisms that all want what they want to survive and thrive. Dr. Aviva Romm, MD uses the phrase “my microbiome made me do it.” Because they’re vote holds a big sway in what we crave, how we feel, and ultimately what we do. Those food choices can impact our neurons, the release of neurotransmitters, and our habitual behaviors. We may crave more sugar, more alcohol, or more fat, because that’s what the majority of our microbiome wants.

Immune Health

These bacteria eat what we eat, and they release waste just like we do. Their waste ends up being metabolites that impact our intestinal health and integrity for good or ill. When the majority of our microbiomes are “on our team,” these metabolites help and support us. For instance, they can produce metabolites like short-chain fatty acids that strengthen the gut lining, prevent leaky gut, and support immunity. Or produce vitamin K, which aids in bone health, or create biofilms that protect us against harmful bacteria or inflammation.

Energy and Metabolism

A healthy gut microbiome supports nutrient absorption, influences glucose metabolism, and even communicates with the ENS to regulate hunger hormones like ghrelin (hunger) and leptin (fullness). Also, when our microbiome is healthy, we don’t have as many cravings for foods that’re bad for us. We actually want more salads and fruits and fiber. And these foods provide us with more nutrition that support our mitochondria (giving us energy), our mood, and our lives.

ACTIONABLE TIPS TO SUPPORT YOUR ENS

• Practice Mindful Eating: Slow down, chew thoroughly, and create a relaxed eating environment to improve digestion.

• Manage Stress: Similar to the parasympathetic actionable tips: practice breathing exercises, yoga, and craniosacral therapy to reduce ENS-disrupting stress.

• Stay Hydrated: It’s basic, but profound. Water supports smooth digestion and helps maintain gut motility (especially improving constipation).

• Avoid Processed Foods: Avoid foods that disrupt the microbiome and ENS function. Trans fats, hydrogenated oils, corn syrup, natural & artificial flavors, sugar & sugar alternative all adversely impact our microbiome and mood.

• Craniosacral Therapy: Calming the body and the mind creates space for the body to innately heal.

• Eat Pre-, Pro-, and Postbiotic-Rich Foods*:

  • Prebiotics are non-digestible food components (usually fibers) that serve as food for the beneficial bacteria (probiotics) in your gut.

  • Foods: garlic, onions, green bananas, asparagus, oats, & chicory root.

  • Supplements: Inulin, fructooligosaccharides (FOS), galactooligosaccharides (GOS), and resistant starches.

  • Probiotics are live microorganisms (primarily bacteria and some yeasts) that can provide health benefits by balancing the gut microbiota.

  • Foods: Fermented foods like yogurt (low sugar), kefir, sauerkraut, kimchi, miso, & tempeh.

  • Supplement Strains: Lactobacillus and Bifidobacterium (bacteria) species or Saccharomyces boulardii (yeast).

  • Postbiotics are the byproducts or metabolites usually produced by probiotics during the fermentation process. These include short-chain fatty acids (SCFAs), enzymes, peptides, and other bioactive compounds.

  • Foods: butter, apple cider vinegar (ACV), flax, chia, & coconut oil.

  • Supplements: Butyrate, acetate, and propionate (SCFAs).

• *If you struggle with IBS or SIBO these seek professional support, as probiotics and prebiotics can sometimes cause more irritation.

I hope this exploration of the ENS inspired you to support your gut-brain axis! If you feel like you’d like more support on your health journey, consider booking an appointment. Or, if you're looking for trusted, high-quality supplements, check out my Fullscript Dispensary. Fullscript ensures access to the best healthcare supplements, with reputable suppliers, guaranteed quality standards, and tools to help you on your wellness journey.

The ENS is truly “at the core” of our health, impacting digestion, mood, immunity, and more. Taking care of your gut is one of the most powerful ways to support overall wellness. Try one or two of the tips above and see how they feel. Next, we’ll dive into the somatic nervous system, the system that lets us move and feel.

What's coming:

• The Autonomic Nervous System - The Intro

  • The Sympathetic Nervous System - "Fight or Flight"

  • The Parasympathetic System and the Vagus Nerve - "Rest & Digest"

  • The Enteric Nervous System - The Gut-Brain Connection

• The Somatic Nervous System - Move & Sense

• The Cranial Nerves - Pathways of Sensory and Motor Control

• Brain Regions and Their Roles in Thought, Mood, and Movement

• How the Nervous System Impacts Mental Health & Trauma Recovery

• Craniosacral Therapy - Enhancing Nervous System Balance

Are there specific areas of the nervous system you're curious about? Drop a comment below, and I'll be sure to cover them as we journey through this incredible body-wide network!

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