The Importance of the Microbiome to Cardiovascular Health

The bacteria the live in our gut and play critical roles in our health change according to the foods we eat
September 7, 2020 Updated: September 7, 2020

What would you think if I told you that the trillions of microbes living in your intestinal tract—referred to as the gut microbiota—contains 100-fold more genes than the rest of your body and that these gut microbiota can have a dramatic impact on your cardiovascular health? This relationship is a prime example of the brain-gut connection.

Experts are uncovering more and more evidence that the gut microbiome has a role in a person’s overall health and chances of developing any disease. Thus far, Type 2 diabetes, metabolic syndrome, and obesity are a few of the conditions that exemplify the impact of host–gut microbiome interactions, and all three have a significant role in cardiovascular health.


The most convincing evidence illustrating a link between the microbiome and cardiovascular health involves a substance called trimethylamine-N-oxide, an organic compound which is made by the liver after bacteria in the intestinal tract digest certain nutrients, including choline, L-carnitine, and lecithin. These nutrients are found in foods such as dairy, meat, eggs, and fish.

The more of these foods you eat, the more trimethylamine-N-oxide your gut microbiota and liver will produce. High levels of trimethylamine-N-oxide (TMAO) are associated with diabetes, hardening of the arteries, colon cancer, chronic kidney disease, and an increased risk of cardiovascular events. At the same time, there are associations between the composition of the microbiome and various risk factors for cardiovascular disease, such as high blood pressure, inflammation, and impaired metabolism.

The relationship between TMAO and cardiovascular risk has gained considerable attention, so much so that experts are exploring new ways to test for this substance in the blood to help predict future risk of heart attack, stroke, and death among people who appear to be healthy otherwise.

One such test was developed by experts at Cleveland Clinic and measures blood levels of TMAO. Basically, the higher a person’s level of TMAO, the more likely he or she is to accumulate cholesterol in their artery walls, which in turn boosts their risk of having a heart attack or stroke.

More specifically, researchers evaluated the strength of the TMAO test and found that individuals who had the highest levels of TMAO had a 2.5 times increased risk for experiencing a major cardiovascular event than those who had the lowest levels during three years of follow-up.

How to reduce TMAO levels

You can take a number of steps to reduce TMAO levels, create a healthier microbiome, and thus lower your risk of cardiovascular events.

Mediterranean, Vegetarian, Vegan Diet: Research has shown that vegans and vegetarians have microbiome bacteria that produce less TMAO than do meat-eaters. The same is true for those who follow a Mediterranean diet, which includes eating more vegetables, fruits, whole grains, and healthy fats, smaller portions of dairy, less red meat, and a weekly intake of fish, poultry, beans, and eggs.

Consume Prebiotics and Probiotics: Prebiotics are plant fibers in fruits and vegetables that nourish probiotics, the beneficial bacteria in the gut. It’s been shown in animal studies that prebiotics and probiotics can reduce TMAO levels. Some food sources of prebiotics include raw garlic, leeks, onions, dandelion greens, chicory root, asparagus, and jicama. Probiotics can be found in fermented vegetables (e.g., sauerkraut, kimchee), yogurt, kefir, and tempeh.

Take Vitamins B and D: At least one study in adults has shown that supplementation with B vitamins (i.e., folic acid and vitamins B6 and B12) along with vitamin D3 (1,200 IU) reduces levels of TMAO.

Use Resveratrol Supplements: This polyphenol, found in the skins of red grapes, red wine, berries, and peanuts, has been shown to reduce blood levels of TMAO in mice prone to atherosclerosis.

Deborah Mitchell is a freelance health writer who is passionate about animals and the environment. She has authored, co-authored, and written more than 50 books and thousands of articles on a wide range of topics. This article was originally published on