Fighting Depression and Anxiety Through the Gut
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Vagus nerve stimulation for mood support (Part 2 of 2)
Last week’s post examined the vagus nerve (the tenth cranial nerve) and the important role it plays in connecting the body to the brain. We explored how breath, laughter, and exercise all “tickle” the nerve to send soothing, calming signals to the brain and thus improve mental health.
Today we’ll take a look at another body system connected to the brain via the vagus nerve: the gut.
Because so many of the fibers of the vagus nerve run are afferent – meaning they travel upwards from the gut to the brain – the health of the digestive system can have a huge impact on mental health and mood, and even other neurological conditions like Alzheimer’s disease.
In fact, studies performed on mice suggest that selective serotonin reuptake inhibitor (SSRI) medications work by contributing to gut-brain signaling along the vagus nerve.
The gastrointestinal microbiome definitely influences the condition of neuropsychiatric disorders.
One of the simplest ways to support the brain via the gut is to maintain an optimal microbial balance (have a healthy mix of “good” bacteria) in the digestive tract. The gastrointestinal microbiome “definitely influences the condition of neuropsychiatric disorders,” according to the scientific literature.
There are several ways by which the microbes in the gut can affect the brain:
The bacteria in the digestive tract directly stimulate the afferent fibers of the vagus nerve, thus influencing the types of signals that get sent to the brain. That is a big part of how and why the gut can influence cognition, memory, and mood. Imbalances in the gut can even drive addictions.
The bacteria in the digestive tract directly influence the types of signals that get sent to the brain.
Gut bacteria contain components such as lipopolysaccharides (LPS) that stimulate the immune system in a low-grade fashion. In the setting of too much “bad” bacteria (dysbiosis), celiac disease, or leaky gut syndrome, however, the immune system gets too stimulated. The bacteria can also produce metabolites (like D-lactic acid and ammonia) that are toxic to the nervous system. All of this results in the production of neurological inflammation – and we now know that inflammation is a major cause of depression.
Bacteria in the gut produce about 95% of the body’s supply of serotonin.
It has also been shown that the microbes in the gut can produce hormones and neurotransmitters – chemicals that are essential for physical, mental, and emotional health. In fact, the bacteria in the gut produce about 95% of the body’s supply of serotonin!
Building a healthy gut microbiome through eating a balanced diet and taking pre- and probiotic supplements can therefore be simple-yet-powerful strategies for supporting brain function and easing depression and anxiety.
Pre- and probiotic supplements can be simple-yet-powerful strategies for supporting brain function.
Once a good microbiome has been created, it is important to avoid disrupting it. One simple way to maintain a healthy microbiome is to avoid taking antibiotics unless they are absolutely necessary, and to supplement with a good quality probiotic supplement after taking antibiotics.
Another way to support the brain via the gut is to avoid gluten, alcohol, refined sugars, and other pro-inflammatory foods. (Check out my article on Ways to Ease Inflammation and Depression for more suggestions.)
The vagus nerve is a superhighway that connects the digestive system to the brain. This is how and why gut health can have huge implications on mood and cognition. Eating healthy, avoiding pro-inflammatory foods, healing leaky gut, and taking a good quality probiotic supplement are all easy and effective ways to support the gut-brain axis.
ReferencesClick here to see References
 Breit S, et al. Vagus nerve as modulator of the brain-gut axis in psychiatric and inflammatory disorders. Front Psychiatry. 2018 Mar 13;9:44. DOI: 10.3389/fpsyt.2018.00044
 Doidoe T, et al. The impact of the microbiota-gut-brain axis on Alzheimer’s disease pathophysiology. Pharmacol Res. 2021 Feb;164:105314. DOI: 10.1016/j.phrs.2020.105314
 McVey Neufeld K-A, et al. Oral selective serotonin reuptake inhibitors activate vagus nerve dependent gut-brain signalling. Sci Rep. 2019 Oct 3;9(1):14290. DOI: 10.1038/s41598-019-50807-8.
 Kakinuma Y. Significance of vagus nerve function in terms of pathogenesis of psychosocial disorders. Neurochem Int. 2021 Feb;143:104934. DOI: 10.1016/j.neuint.2020.104934
 Galland L. The gut microbiome and the brain. J Med Food. 2014 Dec;17(12):1261-72. DOI: 10.1089/jmf.2014.7000
 Dinan TG, Cryan JF. The microbiome-gut-brain axis in health and disease. Gastroenterol Clin North Am. 2017 Mar;46(1):77-89. DOI: 10.1016/j.gtc.2016.09.007
 Livingston M. Top 3 reasons why so many people go gluten-free: celiac disease is only one. San Francisco (CA): CNET; 2020 [cited 2022 Feb 18]. Available from: https://www.cnet.com/health/nutrition/reasons-for-eating-a-gluten-free-diet/
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Dr. Erica Zelfand
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