First, a few quick notes to help you orient within our pages:

• If you’re new, or need a review, here’s the link to the START page.

• You can find last month’s post (our 25th) on the anatomical branches the vagus nerve here.

• Monthly & Supplementary Posts + Recordings can be accessed by topic from the navigation bar atop the Wandering Around Vagus Homepage.

• All past posts are listed in reverse chronological order on the archive page.​

THIS MONTH’S WORK

Last month, we explored the major branches of the vagus nerve and touched on their broader functions. This month, we’re narrowing our focus to examine the specific branches that regulate digestion and support gut health.

The vagus nerve plays three key roles in digestion. First, it influences many processes from the secretion of enzymes in saliva as we chew, to how the lower gut organs move waste out of our body. Secondly, it serves as a primary communication pathway between the brain and the gastrointestinal (GI) tract, orchestrating functions that ensure efficient digestion and nutrient absorption. Thirdly, the gut has its own dedicated nervous system that directly influences mood, cognition, and overall well-being.

This post explores the vagal structures, functions, mechanisms, and broader implications that support gut health and overall well-being.

By the end of this post you’ll have a better sense of:

• the overall role of the vagus nerve in digestive health

• which branches of the vagus nerve are involved in digestion and other functions of the gut

• the bidirectional pathways of the vagus nerve and their role in digestive functioning and health

• the relationship between vagal tone and digestive health

• some common digestive disorders that involve the vagus nerve

• the role of the vagus nerve plays in your own unique digestive system and any issues you have.

Digestive Anatomy and Function of the Vagus Nerve

Let’s start with a more complete list of the digestive functions the vagus nerve is involved in, beginning with our first tastes of a meal:

1. Regulation of Salivation: The vagus nerve stimulates salivary glands, that begin the breakdown of food with digestive enzymes like amylase.

2. Control of Swallowing: It coordinates the muscles involved in swallowing, ensuring the smooth passage of food from the mouth to the esophagus.

3. Esophageal Motility: The vagus nerve facilitates peristalsis, the rhythmic contractions that move food down the esophagus into the stomach.

4. Gastric Secretion and Motility: It stimulates the release of gastric acid and digestive enzymes while promoting stomach contractions that mix food with digestive juices.

5. Regulation of Pancreatic Enzymes: It signals the pancreas to release enzymes necessary for breaking down proteins, carbohydrates, and fats.

6. Bile Release and Liver Function: The vagus nerve aids in bile secretion, which emulsifies fats for absorption.

7. Intestinal Peristalsis: It governs the movement of food through the intestines, ensuring proper nutrient absorption and waste elimination.