Quick answer: The gut-brain axis is the two-way communication network between your gut and brain. It runs through the enteric nervous system, the vagus nerve, the HPA stress axis, immune signals and gut microbes. Chronic stress can change gut motility, immunity and the microbiome, while gut health can influence mood. Diet, mind-body practices and sleep support both.
Key takeaways
The gut-brain axis is a two-way signaling network between the gut and the brain, built on the gut’s own nervous system and the vagus nerve.
Stress activates the HPA axis and cortisol, which can change gut motility, immune function and the gut lining.
Slow breathing, meditation, yoga, fiber-rich foods, exercise and sleep can all support this connection.
What is the gut-brain axis?
A two-way signaling network between the gut and brain. Signals travel both ways, constantly.
How it’s built
It is built from the enteric nervous system, the “second brain” in the gut wall, and the autonomic nervous system, including the vagus nerve. The HPA axis, the stress hormone system, is involved too, along with the gut microbiota: microbes that make signaling molecules.
How stress affects the gut
Stress activates the HPA axis and cortisol, which can change motility, immune function and the gut lining. See stress, sleep and the gut and cortisol.
Mind-body techniques
Meditation and yoga can help, as can slow, deep breathing, which may increase vagal activity.
Food and lifestyle approaches
Fiber, fruit and vegetables feed beneficial microbes, and fermented foods or probiotics can help if appropriate. Regular exercise and sleep matter, along with digestive support if needed, guided by your provider.
The gut-brain axis and healthy aging
Gut-derived inflammation and microbial changes may affect brain health over time. Caring for the gut supports mood, cognition and resilience.
When to see a naturopathic doctor
It may be time to see a naturopathic doctor if you have ongoing bloating, gas, diarrhea or constipation, or food reactions that seem to be multiplying. The same is true if you have fatigue, skin flares or joint aches alongside gut symptoms, or if you want a personalized gut plan instead of guessing.
See a medical provider promptly for blood in your stool, black stools, unexplained weight loss, persistent vomiting, severe abdominal pain, fever, or trouble swallowing.
What the research shows
Some of the first evidence that gut bacteria can influence mood in people came from a 2016 randomized, double-blind trial by Akkasheh and colleagues. Forty adults aged 20 to 55 with major depression took either a probiotic with Lactobacillus acidophilus, Lactobacillus casei and Bifidobacterium bifidum or a placebo for 8 weeks, alongside their usual care. Beck Depression Inventory scores fell by 5.7 points with the probiotic compared with 1.5 points with placebo, and insulin resistance and hs-CRP also improved. With only 20 people per group and a short follow-up, this is early evidence, and probiotics are not a replacement for mental health care.
Diet may matter as much as supplements. In a 2021 Stanford trial by Wastyk and colleagues, 36 healthy adults ate either a high-fiber or a high-fermented-food diet for 17 weeks. The fermented-food group’s gut microbial diversity rose steadily and several inflammatory markers fell, which is relevant because inflammation is one proposed link between the gut and the brain. Mood was not the focus of this study, so it does not show direct effects on mental health.
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Questions to bring to your clinician
These questions can help you get the most out of your next visit.
Could stress be playing a role in my digestive symptoms?
Could stress be affecting my digestion in noticeable ways?
Which stress-relief habits might also help my gut?
Should we look at my gut and my stress together in my plan?
Frequently asked questions
What is the gut-brain axis?
The two-way communication between your gut and brain.
Can stress cause digestive problems?
Yes, through the HPA axis and nervous system.
Can gut health affect mood?
Research suggests links via microbes, inflammation and the vagus nerve.
What helps the gut-brain axis?
Mind-body practices, fiber, fermented foods, sleep and exercise.
Sources
- Akkasheh G, Kashani-Poor Z, Tajabadi-Ebrahimi M, et al. Clinical and metabolic response to probiotic administration in patients with major depressive disorder: A randomized, double-blind, placebo-controlled trial. Nutrition 2016. PMID: 26706022. https://pubmed.ncbi.nlm.nih.gov/26706022/
- Wastyk HC, Fragiadakis GK, Perelman D, et al. Gut-microbiota-targeted diets modulate human immune status. Cell 2021. PMID: 34256014. https://pubmed.ncbi.nlm.nih.gov/34256014/
- Carabotti M, et al. The gut-brain axis: interactions between enteric microbiota, central and enteric nervous systems. Ann Gastroenterol 2015. PMID: 25830558. https://pmc.ncbi.nlm.nih.gov/articles/PMC4367209/
- Breit S, et al. Vagus Nerve as Modulator of the Brain-Gut Axis in Psychiatric and Inflammatory Disorders. Front Psychiatry 2018. PMID: 29593576. https://pmc.ncbi.nlm.nih.gov/articles/PMC5859128/
- Cryan JF, et al. The Microbiota-Gut-Brain Axis. Physiol Rev 2019. PMID: 31460832. https://pubmed.ncbi.nlm.nih.gov/31460832/
- Konturek PC, Brzozowski T, Konturek SJ. Stress and the gut: pathophysiology, clinical consequences, diagnostic approach and treatment options. J Physiol Pharmacol 2011. PMID: 22314561. https://pubmed.ncbi.nlm.nih.gov/22314561/
- Zaccaro A, et al. How Breath-Control Can Change Your Life: A Systematic Review on Psycho-Physiological Correlates of Slow Breathing. Front Hum Neurosci 2018. PMID: 30245619. https://pmc.ncbi.nlm.nih.gov/articles/PMC6137615/
This article is for educational purposes only and is not medical advice. It does not replace an individual evaluation. Talk with your healthcare provider before starting supplements or changing medications, especially if you are pregnant, nursing, or managing a health condition.
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