The Gut-Heart Connection: How the Gut Impacts Heart Health

By Dr. Don Zone, MD

When we think about heart health, it's not always obvious that the microorganisms in our gut could be a contributing factor, but this is what researchers are finding as they delve deeper into the gut microbiome.

What Is the Gut Microbiome?

The Human Microbiome Project (HMP), founded in 2008 by the NIH Common Fund, is an ongoing interdisciplinary project focused on examining the relationship between the microorganisms that live in the human body and their effects on overall health. The human microbiome includes a community of eukaryotes, archaea, bacteria, and viruses that, thus far, total to over 100x more genes than humans. While microscopic in size, these organisms make up about 1-3% of our body weight, adding up to a surprising few pounds for the majority of us!¹

Researchers over the last ten years have found 40+ unique correlations between various bacterial strains and the hormones they produce, such as:²

• Epinephrine: Stimulates the fight-or-flight response
• Norepinephrine: Stimulates the fight-or-flight response
• Dopamine: Regulates movement, motivation, and memory
• Serotonin: Regulates sleep patterns, mood, and digestion
• GABA: Calms the nervous system
• Corticosterone: Increases blood glucose levels

It is becoming clear that there is a symbiotic relationship between these microorganisms and humans, with mutual benefits that span beyond one function. Since these organisms thrive on the nutrients we eat, if we choose to make poor dietary decisions, this can lead to a major change in the types of microorganisms that will flourish. If dietary conditions don’t provide the right nutrients for the beneficial bacteria, hormonal imbalances and subsequent changes in quality of sleep, mood, memory, and digestion may be attributed to their inability to thrive. When it comes to the gut-heart connection, microbial metabolites are exceptionally important in our understanding of maintaining our heart health.

What Can Weaken the Gut-Heart Connection?

Inflammation

Inflammation is a major driver of poor cardiovascular health. It occurs when our bodies are inflamed due to the activation of our immune system through the fight-or-flight response. Continually activated immune cells can harm various parts of the body, including blood vessels.

Scientists found that stress in mice caused more atherosclerotic plaques due to the increase in the body’s levels of hormone noradrenaline.³ When noradrenaline is released, it binds to stem cells in the bone marrow to produce an influx of immune cells that end up lodging themselves in blood vessels and contributing to the size of the fatty plaques. Atherosclerotic plaque can be incredibly detrimental to the cardiovascular system, so reducing stress on the body is imperative to preventing the development of cardiovascular conditions.⁴

Gut microorganisms such as Lactobacillus rhamnosus, L. helveticus, and B. longum, have been shown to alter the levels of GABA and corticosterone in mice, reducing cardiovascular risk factors such as stress and inflammation.⁵ Other bacterial metabolites, like trimethylamine (TMA) and its oxidated version of trimethylamine-N-oxide (TMAO), were found to have a strong link to the development of cardiovascular problems. A review published in the Journal of the American Heart Association found that people who had higher levels of TMAO were 62% more at risk for cardiovascular issues.⁶

Lifestyle Changes to Support a Healthy Gut-Heart Connection

With scientific evidence mounting, it’s becoming clear that a healthy gut microbial environment promotes homeostasis and supports cardiovascular health. Establishing a healthy gut can be as easy as introducing foods into the diet that have prebiotic and probiotic benefits. 

Prebiotic foods are high in fiber and include garlic, onions, bananas, and dandelion roots. Probiotic foods include helpful bacteria such as fermented yogurts, sauerkrauts, kimchi, tempeh, and miso. The prebiotic food acts as a fertilizer for the gut, which can be thought of as a garden. The probiotic helps promote the growth of healthy bacteria by acting as the seeds of the garden. The combination of good quality gut soil and fertilizer, with the right seeds, not only smoothes out any digestive issues but also serve to support a healthy gut-heart connection.

Both prebiotic and probiotic nutrients can be obtained from food sources as well as supplements. Ensuring that you are choosing high-quality, live probiotic supplements is key in obtaining the best results. Make sure to speak with your family physician or nutritionist about various options when it comes to choosing the right supplement. 

As scientists continue to study the fascinating world of microorganisms and their connection to our health, the importance of our relationship with them is becoming more apparent. While our understanding of the heart-gut connection is still in its infancy, it’s indisputable that our gut microorganisms have an effect on our immune system and our inflammatory response through the production of various metabolites. Physicians can educate their patients on potential cardiovascular risks that an unhealthy gut microbiome poses and how to reduce those risks naturally to encourage a healthy gut-heart connection and a flourishing microbial garden.

¹  “About The Human Microbiome - Harvard Health Publishing.” 2018. https://www.health.harvard.edu/staying-healthy/are-gut-bacteria-linked-to-heart-health. Accessed July 9, 2019.

^{2 “Microbial Endocrinology: The Interplay Between the Microbiota… - FEMS.” 2015. https://academic.oup.com/femsre/article/39/4/509/2467625. Accessed July 9, 2019.}

^{3 "Chronic stress: a critical risk factor for atherosclerosis - NCBI." 24 Feb. 2019, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6460614/. Accessed 15 Jul. 2019.}

^{4“How Stress Can Clog Your Arteries - Science.” 2014. https://www.sciencemag.org/news/2014/06/how-stress-can-clog-your-arteries. Accessed July 9, 2019.}

^{5 “Microbial Endocrinology: The Interplay Between the Microbiota… - FEMS.” 2015. https://academic.oup.com/femsre/article/39/4/509/2467625. Accessed July 9, 2019.}

^{6“Healthy gut, Healthy Heart? - Harvard Health Publishing.” 2018. https://www.health.harvard.edu/heart-health/healthy-gut-healthy-heart, Accessed July 9, 2019.}