The Gut-Heart Axis: The Stomach and Heart Connection

Michelle Routhenstein, MS, RD, CDE


March 1, 2023

From family history to lack of physical activity, there are many factors that can impact your cardiovascular health. One surprising factor that may be linked to heart disease is the health of your gut. Emerging research is suggesting that there may be a strong connection between your stomach and heart, also known as the gut-heart axis.

The trillions of bacteria, fungi, and other microbes that live in your digestive system are known as the gut microbiome. Science is just beginning to recognize the complex link between the health of your microbiome and its impact on various systems including your cardiovascular system. Let’s explore the gut microbiome in detail, its potential impact on heart health, and ways you can support the health of both the gut and heart.

Your Gut’s Role in Health

Your gut microbiome is home to a wide variety of microorganisms including bacteria, fungi, parasites, and viruses all of which can play a role in supporting or hindering your health. Thankfully, the majority of the microorganisms in your gut are beneficial to your health and help support the delicate balance of bacteria.

However, when the balance in your gut health is disrupted it can trigger a cascade of negative effects including inflammation and immune system suppression setting the stage for disease. In fact, new research has discovered a connection between the imbalance of gut microbiota, also known as gut dysbiosis, and inflammatory bowel disease, rheumatoid arthritis, obesity, and cardiovascular disease.

A Success Story

Before we dive into the science surrounding the gut-heart axis, I wanted to share a success story with you. In my practice, I see many clients who have heart disease and who also have gut health issues. Together, we develop a plan on how to improve their gut health which in turn helps optimize their cardiovascular risk.

A 64 year old woman came to see me because she had osteoporosis and a high calcium score, and wasn’t sure how to balance her diet with achieving adequate calcium intake without increasing her calcium score/plaque in her arteries. She also wanted to lose 10 pounds of which she had been struggling with for many months.

In our initial evaluation, it was apparent that her weight loss was likely stubborn due to insulin resistance; she had a hemoglobin A1c of 5.7%. Her cholesterol was not optimized because of her diet and gut health leading to a history of sluggish bowel movements. Her calcium intake (along with her magnesium, zinc, and protein intake) could have also been improved by her diet for optimal bone mineral density. 

We worked closely together in my VIP Intensive program over 3 months where we addressed her gut health, insulin resistance, and bone/heart health through a nutrient sufficient diet.  

In just 1 month, she had lost 2.5 inches off her waist (went from 36 ¼ inch to 34 inches, a sign of a reduction in underlying inflammation) and 4.6 pounds. We also improved her gut health significantly where she was having regular optimized blood movements (bristol stool chart 4), a sign of improved gut health. In 3 months, she achieved her goal weight, had more energy, and genuinely felt good. 

Her recent labs (taken after 6 months of implementing these recommendations) were optimal (LDL went from 135mg/dL to 64mg/dL, hgA1c went from 5.7% to 5.2%, and her waist circumference remained at optimal levels of less than 34 inches). She is due for a repeat DEXA scan in 6 months. 

We continued to meet monthly afterward and she has sustained all of these great habits and behaviors for the long run – which is most important for heart attack prevention.

The Connection Between Gut Health and Heart Health

While much of the science has focused on the gut-brain axis, emerging research is beginning to notice a link between the gut-heart axis and its effect on cardiovascular disease. The studies surrounding this research have mainly focused on metabolites, the substances that your gut microbiota produces as a result of breaking down food.

One metabolite in particular known as trimethylamine (TMA), is produced when your gut microbes feed on choline, a nutrient found in red meat, eggs, poultry, and fish. The metabolite TMA gets converted to trimethylamine N-oxide (TMAO) in your liver. TMAO has been linked with an imbalanced gut microbiome, and science is looking closely at its connection to arterial plaque, and an increased risk of cardiovascular events like heart attack and stroke. 

Studies are showing that people with high TMAO levels in their blood may be more likely to experience a heart attack or stroke than those with lower levels. One 2017 systematic review and meta‐analysis found that higher levels of TMAO in the blood were associated with an increased risk of major adverse cardiovascular events.

A 2017 review examining the connection between TMAO and heart health found that elevated blood levels of TMAO were associated with a 67% higher risk of major cardiovascular events, and a 91% higher risk of death from all causes.

Stomach Problems that Affect the Heart

An occasional bout of heartburn or constipation can be a sign that your gut microbiome may be temporarily out of balance. However, when stomach problems persist, it may signal that you’re experiencing gut dysbiosis which when left unchecked, can negatively impact your heart health.

Small intestinal bacterial overgrowth (SIBO) is an imbalance in your gut microbiome that can lead to uncomfortable symptoms like bloating, gas, abdominal pain, and diarrhea. Research is suggesting that there is a connection between SIBO and heart disease. In one study researchers found that people with SIBO had a higher frequency of coronary artery disease (CAD). In fact, the study found that CAD was detected in almost 80% of those with SIBO compared to 40% of those without SIBO. 

It’s important to note that patients with SIBO are often placed on long-term, restrictive diets like the low-FODMAP diet or an elemental diet to help manage the condition. However, these diets can cause a metabolic imbalance that can impact the health of your heart. 

More specifically, these restrictive diets can decrease n-butyrate which is cardio-protective, and increase beta-glucuronidase which can negatively affect your heart health. It is important to work with an experienced dietitian when re-introducing new foods to help restore metabolic balance while managing symptoms.

There also appears to be a link between common GI symptoms like constipation and gastroesophageal reflux disease (GERD) and heart health. One large population-based cohort study found that constipation was associated with an increased risk of all cardiovascular outcomes in the short term and ischemic stroke after five years.

Another study found a strong link between GERD and the development of coronary heart disease (CHD). Researchers also found that a proton pump inhibitor (PPI) used for more than one year may increase the risk of CHD.

Ways to Support a Healthy Microbiome

Nutrition, stress management, and exercise are all ways in which you can support your gut and heart health.  


Since diet plays a significant role in the composition of your gut microbiome, what you feed your gut can affect heart health — for better and for worse. For instance, one type of food that is helpful for gut health is fiber-rich foods like whole grains, avocados, lentils, chia seeds, and berries because they can help support the health of your gut and your heart. Studies have found that diets rich in fiber can help reduce the risk of developing cardiovascular disease (CVD) by reducing blood pressure and other cardio-metabolic risk factors.

Moreover, when digested fiber is broken down to form short-chain fatty acids (SCFAs), like butyrate. Research has shown that these SCFAs can not only promote a healthy gut microbiome but they also play a role in helping to regulate blood pressure control.

There are many other foods that are helpful to optimize your gut health, and working with a Registered Dietitian can help you incorporate more of these foods in your diet in a way that will avoid GI distress associated with these foods.

On the other hand, diets high in processed foods and sugar can encourage the growth of harmful gut microbes that are linked to cardiovascular disease and poor metabolic health. Discussing your whole diet with your Registered Dietitian can help you achieve optimal gut and heart health.

Stress Management

You’re likely familiar with the link between stress and heart health but there appears to be a connection between stress and gut health as well. Studies have shown that stress can alter the gut microbiome contributing to dysbiosis, immune dysregulation, and inflammation. Finding ways to manage stress including meditation, deep breathing techniques, and leaning on social supports can positively impact your heart and gut health.


While exercise can benefit heart health, it can also promote microbial diversity and increase healthy gut bacteria. Recent research suggests that exercise can reduce inflammation and positively influence the gut microbiota composition along with the microbial metabolites produced in the gastrointestinal tract.

The Bottom Line

As you can see the stomach and heart connection link is strong. If you’re experiencing a disruption in your GI health, it’s best not to ignore it. Taking a proactive approach to addressing your stomach issues can also benefit your heart health.

When my clients are experience gut issues, a personalized approach helps us identify the root cause and slowly implement changes to avoid any further GI distress. If you are interested in optimizing both your gut health and your heart health to truly reduce your risk of heart attacks and strokes, I would like to offer you a 15 minute complimentary discovery call to discuss further.


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