A Mind-Blowing Connection: The Gut-Heart Axis

We are presented with an ever-growing body of information about the human body, learning more and more about how interconnected physiological systems really are. One of the more fascinating systems is the gut microbiota.

What does that have to do with electrophysiology and heart health? Apparently, quite a bit!

What is the Gut Microbiome?

Our gastrointestinal (GI) tract is host to an entire ecosystem of bacteria, viruses, fungi, and archaea. It is a complex community of microorganisms that actively interacts with the rest of the body.

In healthy individuals, the gut is dominated by two major bacterial groups: Firmicutes and Bacteroidetes. These two make up about 90% of the microbial population, and the ratio between the two is considered a rough indicator of gut health versus potential disease risk.¹

The gut microbiome has recently been dubbed the “hidden organ” due to its profound influence on our overall health. Digesting our food is a priority of the GI system, but it also produces metabolites (chemicals created during microbial metabolism) such as short-chain fatty acids (SCFAs), trimethylamine (TMA), and secondary bile acids. These metabolites can influence distant organs, including the heart, by regulating inflammation, immune responses, and even nerve signaling.²

What is Gut Dysbiosis?

Gut dysbiosis is an imbalance or disruption in the normal gut microbial community. When the gut flips into dysbiosis, harmful bacteria increase, beneficial bacteria decrease, and overall intestinal flora diversity is reduced. The imbalance can result from several factors, including poor diet (high-fat, low-fiber), chronic stress, medications (especially antibiotics), infections, or natural aging.³

Dysbiosis can become severe enough to compromise the integrity of the intestinal barrier, sometimes called a “leaky gut,” allowing bacterial components like lipopolysaccharide (LPS) to enter the bloodstream. When that happens, these molecules can trigger low-grade systemic inflammation (a chronic, subtle immune response) that affects multiple organs.

What Does the Gut Have to Do with Heart Health and AFib?

Dysbiosis also alters the production of key microbial metabolites such as TMAO, SCFAs, indoxyl sulfate, and bile acids, which have been linked to cardiovascular risk, metabolic dysfunction, and arrhythmias such as atrial fibrillation (AFib).⁴ We’ll explain those in greater detail shortly.

Even though research is in its infancy in understanding the “gut-heart axis,” there is no denying the detrimental effects of chronic inflammation on the body. It’s also hard to ignore the connection between chronic inflammation, disease progression, and the health of our intestines. This is what researchers currently postulate.

One key pathway researchers have explored involves the NLRP3 inflammasome, a protein complex in heart cells that detects stress signals and triggers inflammation. Research in both human and animal models shows that gut dysbiosis, especially in older adults, and through a series of preceding mechanisms, activates NLRP3 in the atria (upper heart chambers). This process promotes atrial fibrosis (scar tissue formation) and electrical instability, both of which heighten AFib risk.⁵

Now back to the microbial metabolites we mentioned earlier in this section:

• TMAO (trimethylamine-N-oxide): Formed from dietary choline and carnitine (primarily from processed meats and dairy foods) by gut bacteria, TMAO promotes fibrosis, inflammation, and arrhythmias, and may enhance other AFib risk factors like hypertension and metabolic syndrome.⁶
• Indoxyl sulfate and bile acids: Oxidative stress, atrial remodeling, and electrical instability can be triggered by these metabolites, further promoting AFib.⁶
• SCFAs (short-chain fatty acids): Low SCFA levels, as commonly seen in dysbiosis, contribute to systemic inflammation and AFib susceptibility.⁷

Maintaining a healthy gut ecosystem may therefore help reduce AFib risk, stabilize heart rhythm, and improve overall cardiovascular health.

An Easy Step to Take

One of the easiest ways to tackle chronic inflammation and disease progression is via our diets. Yes, it’s that simple. That’s not to say you should ignore physician advice or medications; they absolutely have a place and part to play in regulating your health. In addition to those medical suggestions, take a look at your diet.

How often are you eating out? When you cook a meal at home, does it come out of a box? Ultra-processed foods are those that have been processed beyond recognition of their original form. Whole foods, on the other hand, are straight off the vine, so to speak. An apple-flavored fruit snack versus an actual apple, for instance. Whole foods deliver maximum nutritional value and, in doing so, better equip the body to fend off inflammatory markers and disease instigators.

Research shows that certain dietary patterns can directly influence gut microbiota and the metabolites they produce, which in turn affect heart health.⁸ Diets high in fiber, plant-based foods, and polyphenols help feed beneficial gut bacteria, boost the production of anti-inflammatory SCFAs, and maintain gut barrier integrity. Conversely, high intake of red meat, fried chow, processed foods, and choline can increase production of TMAO. Simple swaps for more vegetables, legumes, and whole grains can help shift the gut ecosystem toward a healthier, heart-protective state.

Dr. Andrea Tordini is a board-certified cardiac electrophysiologist with specialized fellowship training in diagnosing and treating abnormal heart rhythms.

Dr. Tordini is a part of Florida Medical Clinic Orlando Health

1. Gawałko, M., Agbaedeng, T. A., Saljic, A., Müller, D. N., Wilck, N., Schnabel, R., Penders, J., Rienstra, M., van Gelder, I., Jespersen, T., Schotten, U., Crijns, H. J. G. M., Kalman, J. M., Sanders, P., Nattel, S., Dobrev, D., & Linz, D. (2022). Gut microbiota, dysbiosis and atrial fibrillation. Arrhythmogenic mechanisms and potential clinical implications. Cardiovascular research, 118(11), 2415–2427. https://doi.org/10.1093/cvr/cvab292.
2. Marinacci, B., Mencarelli, N., Stornelli, G., Pellegrini, B., Amedei, A., Gallorini, M., & Grande, R. (2025). Correlation Between Dysbiosis and Atrial Fibrillation: What’s New? International Journal of Molecular Sciences, 27(1). https://doi.org/10.3390/ijms27010073.
3. Karakasis, P., Pamporis, K., Theofilis, P., Milaras, N., Vlachakis, P. K., Grigoriou, K., Patoulias, D., Karamitsos, T., Antoniadis, A. P., & Fragakis, N. (2025). Inflammasome Signaling in Cardiac Arrhythmias: Linking Inflammation, Fibrosis, and Electrical Remodeling. International journal of molecular sciences, 26(13), 5954. https://doi.org/10.3390/ijms26135954.
4. Gawałko, M., Agbaedeng, T. A., Saljic, A., Müller, D. N., Wilck, N., Schnabel, R., Penders, J., Rienstra, M., van Gelder, I., Jespersen, T., Schotten, U., Crijns, H. J. G. M., Kalman, J. M., Sanders, P., Nattel, S., Dobrev, D., & Linz, D. (2022). Gut microbiota, dysbiosis and atrial fibrillation. Arrhythmogenic mechanisms and potential clinical implications. Cardiovascular research, 118(11), 2415–2427. https://doi.org/10.1093/cvr/cvab292.
5. Karakasis, P., Pamporis, K., Theofilis, P., Milaras, N., Vlachakis, P. K., Grigoriou, K., Patoulias, D., Karamitsos, T., Antoniadis, A. P., & Fragakis, N. (2025). Inflammasome Signaling in Cardiac Arrhythmias: Linking Inflammation, Fibrosis, and Electrical Remodeling. International journal of molecular sciences, 26(13), 5954. https://doi.org/10.3390/ijms26135954.
6. Gawałko, M., Agbaedeng, T. A., Saljic, A., Müller, D. N., Wilck, N., Schnabel, R., Penders, J., Rienstra, M., van Gelder, I., Jespersen, T., Schotten, U., Crijns, H. J. G. M., Kalman, J. M., Sanders, P., Nattel, S., Dobrev, D., & Linz, D. (2022). Gut microbiota, dysbiosis and atrial fibrillation. Arrhythmogenic mechanisms and potential clinical implications. Cardiovascular research, 118(11), 2415–2427. https://doi.org/10.1093/cvr/cvab292.
7. Marinacci, B., Mencarelli, N., Stornelli, G., Pellegrini, B., Amedei, A., Gallorini, M., & Grande, R. (2025). Correlation Between Dysbiosis and Atrial Fibrillation: What’s New? International Journal of Molecular Sciences, 27(1). https://doi.org/10.3390/ijms27010073.
8. Gawałko, M., Agbaedeng, T. A., Saljic, A., Müller, D. N., Wilck, N., Schnabel, R., Penders, J., Rienstra, M., van Gelder, I., Jespersen, T., Schotten, U., Crijns, H. J. G. M., Kalman, J. M., Sanders, P., Nattel, S., Dobrev, D., & Linz, D. (2022). Gut microbiota, dysbiosis and atrial fibrillation. Arrhythmogenic mechanisms and potential clinical implications. Cardiovascular research, 118(11), 2415–2427. https://doi.org/10.1093/cvr/cvab292.