By now, most of us are aware that the gut, brain and body are connected in ways beyond digestion. Just a decade ago, leaky gut – more formally known as intestinal permeability – was dismissed as a “pseudoscientific concept” with no bearing on health or disease. Today, Intestinal permeability is recognized as a potential factor in various conditions, including inflammatory bowel, autoimmune, neurodegenerative and even neoplastic diseases (1,2).  Similar leaps are being made in our understanding of the gut microbiome and how when its imbalanced (a process called “dysbiosis”), it may contribute to anything from degenerative disc disease to psychiatric illness to cardiovascular disease (3, 4, 5).

While a whole textbook can be written on this topic, I’m going to take a wild stab at simplifying (hopefully without completely butchering) these concepts. Essentially, there are two crucial components to gut health: 1. intestinal barrier integrity (the converse of leaky gut/intestinal permeability) and 2. a diverse, pathogen-free gut microbiome. If the gut barrier loses its integrity, excess food particles and bacterial pathogens can enter the blood stream – leading to an overactive immune system and inflammation. Additionally, when the gut microbiome becomes imbalanced – this leads to less anti-inflammatory byproducts made by our ‘good’ bacteria and more of the pro-inflammatory byproducts made by the ‘bad’ guys. Since inflammation is a key driver of most chronic diseases, it’s no surprise that both the loss of gut barrier integrity and an imbalanced microbiome are closely linked to a wide range of health conditions.

So low-grade inflammation may explain why gut health relates to different diseases throughout the body, but how does it relate directly to brain health? The most intricate connection between the gastrointestinal (GI) system and brain is through the vagus nerve. This famous and be-loved nerve transmits signals between the brain and the GI system. Because of this two-way communication, the health of the gut doesn’t just impact the brain, but the health of the brain (and vagus nerve in particular) impacts the gut as well. This is why we not only see neurodegenerative conditions (like Parkinson’s Disease) linked to gut inflammation, but we also see inflammatory GI diseases when there is diminished output from the brain back to the gut. In a modern approach to health care, it is essential that we leverage these pathways. This is done by improving the “quality” of these signals between the gut and brain. We can enhance the quality of these signals by optimizing the two key components of gut health by simultaneously improving the vagus-to-gut pathway.

As research continues to deepen our understanding of the gastrointestinal system and its far-reaching impact on the rest of the body, it’s becoming clear that maintaining gut health is crucial for overall well-being. From digestive disorders to neurodegenerative diseases and even chronic pain, maybe Hippocrates was on to something when he famously proclaimed, “All disease begins in the gut.” Modern science is now affirming this insight, and it’s time for modern medicine to keep up.

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References:

1. Pardo-Camacho C, Espín-Jaime B, Martín-Torres M, Núñez-Montero B, Plaza-Díaz J. The Role of Intestinal Permeability in the Development of Non-Alcoholic Fatty Liver Disease: A Comprehensive Review. Int J Mol Sci. 2020;21(13): 4787. doi:10.3390/ijms21134787.
2. Fasano A. Zonulin, Regulation of Tight Junctions, and Autoimmune Diseases. Ann N Y Acad Sci. 2012;1258(1):25-33. doi:10.1111/j.1749-6632.2012.06538.x.
3. Houser, M.C., Tansey, M.G. The gut-brain axis: is intestinal inflammation a silent driver of Parkinson’s disease pathogenesis?. npj Parkinson’s Disease3, 3 (2017). https://doi.org/10.1038/s41531-016-0002-0
4. Andrioaie IM, Duhaniuc A, Nastase EV, et al. The Role of the Gut Microbiome in Psychiatric Disorders. Microorganisms. 2022;10(12):2436. Published 2022 Dec 9. doi:10.3390/microorganisms10122436
5. Novakovic M, Rout A, Kingsley T, et al. Role of gut microbiota in cardiovascular diseases. World J Cardiol. 2020;12(4):110-122. doi:10.4330/wjc.v12.i4.110