April 2026
The Gut Brain Axis
Did you know that there is a bidirectional communication system between the gut and the brain? Ayruvedic medicine refers to the gut as the “second brain” and western research is showing that this is a vital communication pathway that influences both physical and mental health; gut health affects mental health and vice versa.
This pathway is governed by the vagus (wandering) nerve, the longest cranial nerve, which runs from the brainstem to the digestive tract. The vagus nerve is part of the nervous system and controls heart rate, blood pressure, breathing, digestion and immune responses.
The gut microbiome (which is largely found in the intestines) consists of microbes that break down the nutrients in food for absorption, synthesize vitamins and amino acids, and stimulate the immune system, breaking down any potential toxins. These microbes also produce chemical neurotransmitters or messengers that allow the brain and gut to communicate information about hunger, satiety, thirst, hormone regulation, sleep, healing, digestion, and mood. More than 90% serotonin is produced in the gut, and this neurotransmitter sends messages to the brain via the vagus nerve. Serotonin regulates mood, sleep, cognition and digestion.
If the gut becomes compromised, or there are more harmful than beneficial bacteria present, the communication pathway can get muddled and may contribute to a host of inflammatory symptoms and chronic conditions: irritable bowel syndrome, diabetes, obesity, fatigue, anxiety, and depression.
Diet and lifestyle changes, smoking cessation, limiting or eliminating exposure to environmental chemicals and pesticides, along with exercise, can help to improve your gut health which ultimately improves your mental health. It’s a two-way system.
The next blog will present some ideas to consider implementing which research shows may improve your gut health. In the meantime, check out the links to learn more.
Denise Andreas, dandreas@swcaa.org
https://feinstein.northwell.edu/news/insights/vagus-nerve
https://pmc.ncbi.nlm.nih.gov/articles/PMC4425030
https://www.cedars-sinai.org/stories-and-insights/healthy-living/stimulating-the-vagus-nerve