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The Gut-Brain Relationship is Intimate


The Gut-Brain Relationship

We tend to think that the brain has ultimate jurisdiction over everything that goes on in our bodies, but the gut-brain relationship is very close. In fact, the nerves and neurons of the gut enteric nervous system (ENS) often influence brain function. The ENS contains the same amount of nerve cells as the spinal cord, 90 percent of the serotonin and 50 percent of the dopamine in the body. It governs functions such as absorption, digestion, and movement of what we eat and drink.

The gut and ENS “talk” to the brain through the vagus nerve, forming the gut-brain connection. Almost counter-intuitively, 90 percent of the signals sent via the vagus nerve are sent to the brain from the ENS. (That’s a lot of information that our gut is giving our brains!) Even in cases where the vagus nerve is cut (thus dissolving gut-brain communication), the gut is still able to perform all of its operations.

All of this information is really cool, but why is our gut considered our ‘second brain’? The gut, and ENS, are responsible for one of the most important functions our body does. They turn the environment around us into usable energy. Without this operation, we would simply cease to exist. It’s the guts ability to function independently from our brain that ensures the continuation of the operation most essential to our survival. 2 The nature of the gut-brain relationship is a constant revelation. Here are some things you may want to know about it:

You Are What You Eat—or rather, You Feel What You Eat!

Signals from the gut to the brain seem to affect mood. Studies demonstrate that stimulation of the vagus nerve can improve mood.4 In addition, during a recent study, subjects received intragastric infusions of either a saline or fatty acid solution. The subjects that received the infusion of fatty acids were more resistant to sad emotion cues (such as music and pictures) than those who received saline. Receptors in the stomach/gut lining detect fatty acids we eat. As a result, feel-good nerve signals are sent to the brain, supposedly counteracting cues of sadness.6

Stop Stressin’ Cause You’re Messin’ With Your Appetite!

Stress causes the gut to make more of the hormone ghrelin. Ghrelin reduces feelings of anxiousness and sadness. It also stimulates the activation of dopamine in the brain through signals sent via the vagus nerve.3 But, the release of ghrelin in the gut also increases food intake. If you tend to stress eat, ghrelin could be one of the culprits. 5

The Blues and Bacteria

Further compounding the gut-brain interaction, a study revealed good bacteria in the gut can modulate the GABAergic system in the brains of mice. Bacteria in the gut interact with the ENS. They can even send signals through the vagus nerve and the GABAergic system. This could mean that the existence of good bacteria in the gut may ward away symptoms of anxiousness and sadness. Therefore, a healthy dose of probiotics could be useful in improving mood or overall well-being.1

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1) Bravo, J. A., Forsythe, P., Chew, M. V., Escaravage, E., Savignac, H. M., Dinan, T. G., … & Cryan, J. F. (2011). Ingestion of Lactobacillus strain regulates emotional behavior and central GABA receptor expression in a mouse via the vagus nerve. Proceedings of the National Academy of Sciences,108(38), 16050-16055.

2) Cryan, J. F., & O’Mahony, S. M. (2011). The microbiome‐gut‐brain axis: from bowel to behavior. Neurogastroenterology & Motility, 23(3), 187-192.

3) Lutter, M., Sakata, I., Osborne-Lawrence, S., Rovinsky, S. A., Anderson, J. G., Jung, S., … & Zigman, J. M. (2008). The orexigenic hormone ghrelin defends against depressive symptoms of chronic stress. Nature neuroscience,11(7), 752-753.

4) Marangell, L. B., Rush, A. J., George, M. S., Sackeim, H. A., Johnson, C. R., Husain, M. M., … & Lisanby, S. H. (2002). Vagus nerve stimulation (VNS) for major depressive episodes: one year outcomes. Biological Psychiatry, 51(4), 280-287.

5) Skibicka, K. P., Hansson, C., Alvarez-Crespo, M., Friberg, P. A., & Dickson, S. L. (2011). Ghrelin directly targets the ventral tegmental area to increase food motivation. Neuroscience, 180, 129-137.

6) Van Oudenhove, L., McKie, S., Lassman, D., Uddin, B., Paine, P., Coen, S., … & Aziz, Q. (2011). Fatty acid–induced gut-brain signaling attenuates neural and behavioral effects of sad emotion in humans. The Journal of clinical investigation, 121(8), 3094.


Sanesco Health

Sanesco Health

Disclaimer: The information provided is only intended to be general educational information to the public. It does not constitute medical advice. If you have specific questions about any medical matter or if you are suffering from any medical condition, you should consult your doctor or other professional healthcare provider.

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