The parasympathetic “rest and digest” branch of your nervous system promotes gut health and has been found to reduce intestinal permeability or leaky gut.
More specifically, your vagus nerve – the principal component of your parasympathetic nervous system – senses your gut microbiome and responds by dampening inflammation which decreases intestinal permeability (i.e. leaky gut), according to research on The Vagus Nerve at the Interface of the Microbiota-Gut-Brain Axis.
As you may know, your body prioritizes survival. This means that when you perceive any kind of mental, physical or emotional threat, the sympathetic “fight or flight” branch of your autonomic nervous system, which controls all automatic functions in your body including digestion, allocates resources toward survival — blood flow is routed away from the organs of digestion and toward the limbs and muscles so you can quickly flee from danger.
You cannot properly support motility or assimilate your nutrients when blood flow is routed away from your digestive system. When motility and nutrient assimilation are compromised, the tight junctions in the epithelial lining of the gut lose their integrity. This allows pathogens, toxins, undigested food, and bacteria to move through the bloodstream igniting the immune system causing an inflammatory response (i.e. leaky gut).
Similar research on vagal nerve stimulation protecting against stress-induced intestinal barrier dysfunction has found that activating your parasympathetic nervous system turns on your ability to digest, absorb and assimilate your nutrients and “consistently reduces paracellular permeability of the small intestine.”
In other words, activating your parasympathetic nervous system was found to improve intestinal barrier function (i.e. decrease intestinal permeability) and reduce inflammation by increasing the expression of tight junction proteins along the cell membrane of intestinal cells.
How Parasympathetic Nervous System Supports Gut Health
Your vagus nerve, or cranial nerve #10, is the main line of communication between your brain and your gut, also known as the gut-brain axis. It is also the gear shift between the sympathetic and parasympathetic branches of your nervous system.
It is your vagus nerve that helps your brain communicate with your gut and your gut communicate with your brain, sending signals in both directions to help your body to perform involuntary actions, like digesting your food.
In relation to gut health, your vagus nerve recognizes changes in your gut’s microbiome and sends this message to the brain. When your parasympathetic nervous system is active, your vagus nerve can focus on repair and maintenance, allowing the brain to respond with the appropriate digestive signal immediately. This is known as your “cholinergic anti-inflammatory pathway” which travels through your vagus nerve fibers and is “able to dampen peripheral inflammation and to decrease intestinal permeability, thus very probably modulating microbiota composition.” For example, if you eat an inflammatory food such as gluten or dairy, your vagus nerve recognizes this inflammation and alerts your brain. Your brain then alerts your immune system to facilitate an inflammatory response.
If your vagus nerve is prioritizing survival (stuck in sympathetic dominance), the signal is not prioritized and the brain might miss important information, allowing inflammation to become chronic, which contributes to leaky gut and autoimmune conditions.
Vagus Nerve Triggers Digestion
Signals from your brain, sent via your vagus nerve, help regulate various digestive functions, including gastric motility, acid secretion, and sphincter activity.
In order to properly assimilate nutrients, you need to eat in the parasympathetic “Rest, Digest and Heal” state. Stimulating your vagus nerve with Parasympathetic® oil triggers your parasympathetic response, which turns on your digestive process in the following ways:
Stimulates Secretion of Saliva: Your vagus nerve innervates the salivary glands of the mouth and stimulates the release of salivary enzymes which helps to break down the food before it enters the esophagus.
Releases stomach acid: Your vagus nerve regulates and supports optimal production and secretion of gastric fluids, like hydrochloric acid (HCL) and pepsin which help break down the complex particles of the food you ingest, especially protein, into simpler forms that can be absorbed in the later stages of digestion.
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Gastric Motility: Your stomach operates through a series of coordinated events, collectively known as gastric motility and secretion. Upon the ingestion of food, your stomach initiates mechanical and chemical processes to facilitate digestion. The walls of the stomach contain layers of smooth muscles that contract and relax in a coordinated manner, churning the food and mixing it with digestive juices. The vagus nerve stimulates the smooth muscles in the stomach wall. This stimulation is crucial for the initiation of peristaltic waves, which are rhythmic contractions and relaxations of the muscles. Peristalsis propels the partially digested food, known as chyme, toward the lower part of the stomach and eventually into the small intestine.
Stimulates Release of Digestive Enzymes: Your pancreas produces and secretes digestive enzymes into your digestive tract through a duct into your duodenum to aid in nutrient absorption and help neutralize your stomach acids. These pancreatic enzymes work in tandem with bile from your gallbladder to help break down food for proper digestion and absorption. Enzymes produced by your pancreas for digestion include:
- Lipase to digest fats
- Amylase to digest carbohydrates
- Chymotrypsin and Trypsin to digest proteins
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Stimulates Release of Bile: Your gall bladder stores and concentrates bile, a yellowish-green fluid that is produced in the liver. When you eat a meal that contains fat, your gall bladder secretes bile to help emulsify the fat for digestion.
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Gut Motility and Nutrient Absorption: Gut motility – or the rhythmic contractions of your digestive system – is facilitated by your vagus nerve which orchestrates the stimulation of smooth muscle contractions in the gastrointestinal tract, facilitating the movement of ingested food by opening and closing sphincters – including the pyloric sphincter, which regulates the movement of partially digested food from the stomach into the small intestine — allowing nutrients and waste to move through the digestive system and be properly absorbed or eliminated. Your vagus nerve creates a wave-like action in the small intestine to help move the food through to the large intestine. This stimulatory effect is mediated by the release of acetylcholine, a neurotransmitter that triggers muscle contractions vital for effective digestion.
Tight Junction Integrity: Your vagus nerve serves as a sensory conduit, relaying information about the state of the gut to the brain by monitoring the conditions inside the digestive organs. It provides the brain with essential information on the condition of the digestive tract, and the health of microbes in the gut, allowing for adaptive changes to help maintain the integrity or normal permeability of gut lining. This ensures that the gut interface is tightly sealed and only nutrients get into the blood while inflammatory substances and bugs are kept out. When the sympathetic nervous system is more active, your gut becomes more permeable, allowing inflammatory provoking substances to enter the bloodstream.
When you attempt to eat under stress, in a sympathetic state, you compromise your ability to assimilate your nutrients and eliminate waste. To support optimal brain function and enhance digestion, apply Parasympathetic® behind the earlobe on the mastoid bone before meals. When you apply it, take a few deep breaths, with the exhalation longer than the inhalation to fully relax and turn on digestion prior to meals.
