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The Link Between Your Gut and Heart Health - Everyday Health

Cardiovascular disease — affecting the heart and blood vessels — is the leading cause of mortality worldwide and in the United States, where it accounts for about 1 in 4 deaths, according to the Centers for Disease Control and Prevention. Many factors can increase the risk of developing heart disease, including being overweight or obese, lack of physical activity, and smoking. But there's an important factor you may not be aware of: gut health.

In recent years, there’s been an increase in public awareness of the gut microbiome, the collection of bacteria and other microorganisms that live in your digestive system, and the role it plays in digestive health. By improving the health of your gut microbiome, you may be able to reduce bloating and gas and improve the regularity of bowel movements.

A growing body of research suggests that the wrong balance of gut bacteria can cause harm beyond your gut, playing a role in conditions as different as arthritis, obesity, and depression. It also appears to affect your blood vessels. In fact, chemicals or processes related to gut bacteria have been tied to a higher risk of heart failure, atherosclerosis (plaque buildup in arteries), and major cardiovascular events like heart attack and stroke, notes a review of studies published in March 2020 in the journal Microbiome .

While the research is ongoing, the good news is that you can take steps to improve your gut microbiome, from modifying your diet to taking certain supplements and adopting other healthy lifestyle measures. Here’s what you should know about the connection between gut and heart health, and how to maximize your gut health according to the latest data.

RELATED: How Your Gut Microbiome Affects Your Health

Your Gut’s Role in Health and Disease

Your microbiome consists of trillions of microorganisms that live in and on your body — mostly bacteria but also fungi and other organisms. It’s estimated that an average person has about 38 trillion bacteria in their microbiome, with most of these creatures living in the digestive tract, or gut.

Many of these bacteria are considered beneficial, aiding in the normal functions of your digestive system and helping defend your body against more harmful organisms.

Other bacteria in your microbiome, however, can not only disrupt your digestive health but negatively affect many other areas of your body, too. “There’s significant evidence that the gut microbiome is involved in human health in virtually all diseases,” says Raphael Kellman, MD, a physician of integrative and functional medicine and founder of the Kellman Wellness Center in New York City. “Cardiovascular diseases, which are associated with high morbidity and mortality across the world, are no exception.”

While there’s still a lot to learn about how exactly the gut microbiome affects different disease risks, it’s clear that broadly speaking, an unhealthy gut causes negative health effects through inflammation — your immune system’s reaction to an injury or foreign substance.

“Seventy percent of the body’s inflammatory cells are actually housed in the gut-associated tissue,” explains Ian R. Barrows, MD, a cardiology fellow at the George Washington University School of Medicine and Health Sciences in Washington, DC. “So the gut bacteria have an influence on the inflammatory role of the gut and the whole body.”

When your gut becomes inflamed, Dr. Kellman says, substances that shouldn’t leave your intestine, including chemicals produced by unhealthy gut bacteria, can enter your bloodstream and cause an inflammatory reaction wherever they end up in your body. To get anywhere, these pro-inflammatory substances have to travel through — and can affect — your blood vessels.

When inflammation affects blood vessels, “the vessels lose their elasticity,” Kellman explains. “The cells of the vessels don’t function well, and that sets the stage for the development of plaque and atherosclerosis.”

The Gut’s Impact on Cardiovascular Health: What We Know

In just the past few years, research studies have produced mounting evidence that an unhealthy gut microbiome can contribute to cardiovascular disease. Many studies have focused on an inflammatory marker called trimethylamine‐N‐oxide (TMAO), which is produced due to the presence of certain unhealthy gut bacteria.

In a review of 19 studies on TMAO and cardiovascular risk, published in June 2017 in the Journal of the American Heart Association , researchers found that elevated TMAO was associated with a 62 percent higher risk of major cardiovascular events like heart attack and stroke, and a 63 percent higher risk of death from all causes, during the study period. These results were fairly consistent across the study populations, which included people undergoing elective coronary angiography and those with chronic kidney disease, with or without diabetes, with chronic or acute heart failure, and with coronary or peripheral artery disease.

A similar review of 17 studies on TMAO and heart risk, published in October 2017 in the European Heart Journal , found that high blood levels of TMAO were associated with a 67 percent higher risk of major cardiovascular events, along with a 91 percent higher risk of death from all causes. This death risk increased in proportion with levels of TMAO, not just at very high levels, and was consistent across the study populations.

It’s important to note, says Kellman, that according to the available data, “even with the adjustment of traditional risk factors” — taking into account differences in blood pressure, cholesterol, or triglycerides — “an elevated TMAO level can predict an increased risk of cardiovascular events.”

Another notable — and possibly hopeful — finding occurred in a study of mice coauthored by Dr. Barrows, published in October 2018 in the journal Scientific Reports . In that study, mice with atherosclerosis were fed a beneficial type of bacteria that uses TMAO for food, which resulted in lower levels of TMAO in their blood. What’s more, “after they were given these beneficial bacteria, the amount of atherosclerotic plaque actually decreased,” Barrows explains. While there haven’t been any studies to look for a similar benefit in humans with atherosclerosis, “hopefully it’s not far away,” he adds.

How to Maintain a Healthy Gut Microbiome

Two types of dietary supplements are often touted as supporting a healthy gut microbiome: probiotics and prebiotics. Probiotics contain beneficial bacteria, while prebiotics contain substances that can promote the growth of beneficial bacteria. Some supplements contain both probiotics and prebiotics.

While there’s evidence that some types of these supplements may be beneficial to your gut health, Barrows recommends caution. “I still don’t think we have a great understanding of whether giving someone probiotics or prebiotics would actually reduce inflammation and cardiovascular disease in the long run,” he says.

Kellman notes that in addition to probiotics and prebiotics, certain foods can be beneficial to maintaining a healthy gut microbiome. These include the following foods, according to the Center for Applied Nutrition at the University of Massachusetts Medical School:

  • Asparagus
  • Leeks
  • Dandelion greens
  • Garlic
  • Onions
  • Flaxseed
  • Apples
  • Bananas
  • Steel-cut oats
  • Cocoa

It’s also important to avoid processed foods, refined carbohydrates, excess sugar, and excess fat in your diet, all of which can lead to an unhealthy microbiome, says Kellman. Barrows adds that alcohol can also upset your gut balance, so it’s best to drink in moderation, if at all.

Stress can be another key factor in an unhealthy balance of gut bacteria, Kellman notes, so reduce stress whenever possible, possibly through activities like exercise, meditation, or mindfulness exercises.

Whether you currently have heart disease or are at an increased risk for it, recognizing the role of the gut microbiome in human health is critical, says Kellman. He believes that improving the microbiome is vital to maintaining overall health and preventing disease.

For now, says Barrows, “the most important takeaway from this, I think, is that there’s more to come." The link between gut and heart health, he notes, is “a really exciting field, and hopefully we’ll have more suggestions in coming years.”