Study shows gut bacteria byproduct predicts heart attack and stroke

April 24, 2013, Cleveland Clinic

A microbial byproduct of intestinal bacteria contributes to heart disease and serves as an accurate screening tool for predicting future risks of heart attack, stroke and death in persons not otherwise identified by traditional risk factors and blood tests, according to Cleveland Clinic research published today in The New England Journal of Medicine.

The research team was led by Stanley Hazen, M.D., Ph.D., Vice Chair of Translational Research, Chair of the Department of Cellular and for the Lerner Research Institute and section head of Preventive Cardiology & Rehabilitation in the Miller Family Heart and Vascular Institute at Cleveland Clinic, and W.H. Wilson Tang, M.D., Department of Cardiovascular Medicine in the Miller Family Heart and Vascular Institute and Lerner Research Institute.

The current study is an extension of Dr. Hazen's previous work, in which he found that a chemical called trimethylamine N-oxide (TMAO) is produced when intestinal bacteria digest the nutrient phosphatidylcholine, commonly known as lecithin. The prior research showed that TMAO levels in the blood were associated with heart disease. Dr. Hazen and colleagues have now confirmed that are essential in forming TMAO in humans and demonstrated a relationship between TMAO levels and future cardiac events like , stroke, and death—even in those with no prior evidence of cardiac disease risk.

To demonstrate the role of gut flora in forming TMAO, human subjects were asked to eat two hard-boiled eggs (a common dietary source of lecithin) and a capsule of labeled lecithin (as a tracer). After ingestion, TMAO levels in the blood increased. However, when these same subjects were given a brief course of broad-spectrum antibiotics to suppress their gut flora, their TMAO levels were suppressed, and no additional TMAO was formed, even after ingesting lecithin. These results demonstrated that the are essential for the formation of TMAO.

In the second phase of the study, the researchers measured TMAO levels in a large, independent, clinical cohort – consisting of more than 4,000 adults undergoing cardiac evaluation at Cleveland Clinic – over a three-year follow-up period. They found that higher TMAO blood levels were associated with higher future risks of death and nonfatal heart attack or stroke over the ensuing three-year period, independent of other risk factors and results. These results complement those of another recent study of Dr. Hazen's linking gut flora metabolism of a structurally similar nutrient found in animal products, carnitine, to TMAO production and heart attack risk.

"Heart disease remains the No. 1 killer, and while we know how to reduce cholesterol, treat blood pressure, and reduce cardiac risks through diet and other interventions, a substantial residual risk still remains," Dr. Hazen said. "We need to find new pathways to attack heart disease, and these findings strongly suggest that further research into the involvement of gut microbiome in the development of cardiovascular disease could lead to new avenues of prevention and treatment of ."

Dr. Hazen further suggested, "These studies show that measuring blood levels of TMAO could serve as a powerful tool for predicting future cardiovascular risk, even for those without known risk factors. More studies are needed to confirm that TMAO testing, like cholesterol, triglyceride or glucose levels, might help guide physicians in providing individualized nutritional recommendations for preventing cardiovascular disease. Our goal is not to suggest dietary restrictions of entire food groups. Eggs, meat and other animal products are an integral part of most individuals' diets. Our work shows, however, that when digesting these foods, gut flora can generate a chemical mediator, TMAO, that may contribute to cardiovascular disease."

Explore further: Researchers find link between common dietary fat, intestinal microbes and heart disease

More information: Full Text (subscription or payment may be required)
Editorial (subscription or payment may be required)

Related Stories

Researchers find link between common dietary fat, intestinal microbes and heart disease

April 6, 2011
A new pathway has been discovered that links a common dietary lipid and intestinal microflora with an increased risk of heart disease, according to a Cleveland Clinic study published in the latest issue of Nature.

Researchers discover new link between heart disease and red meat

April 7, 2013
A compound abundant in red meat and added as a supplement to popular energy drinks has been found to promote atherosclerosis – or the hardening or clogging of the arteries – according to Cleveland Clinic research published ...

L-carnitine significantly improves patient outcomes following heart attack

April 12, 2013
L-carnitine significantly improves cardiac health in patients after a heart attack, say a multicenter team of investigators in a study published today in Mayo Clinic Proceedings. Their findings, based on analysis of key controlled ...

Research shows blood protein levels may predict risk of a cardiovascular event

April 8, 2011
Increased levels of a protein that helps regulate the body's blood pressure may also predict a major cardiovascular event in high-risk patients, according to a study led by St. Michael's Hospital's cardiovascular surgeon ...

Could 'friendly' gut bacteria help fight heart disease?

July 17, 2012
(Medical Xpress) -- Scientists at the University of Reading are looking at ways of tackling heart disease and diabetes - through our guts.

The microbiome and disease: Gut bacteria influence the severity of heart attacks in rats

January 13, 2012
New research published online in the FASEB Journal (http://www.fasebj.org) suggests that the types and levels of bacteria in the intestines may be used to predict a person's likelihood of having a heart attack, and that manipulating ...

Recommended for you

Higher risk of heart attack on Christmas Eve

December 12, 2018
The risk of heart attack peaks at around 10pm on Christmas Eve, particularly for older and sicker people, most likely due to heightened emotional stress, finds a Swedish study in this week's Christmas issue of The BMJ.

Your weight history may predict your heart failure risk

December 12, 2018
In a medical records analysis of information gathered on more than 6,000 people, Johns Hopkins Medicine researchers conclude that simply asking older adult patients about their weight history at ages 20 and 40 could provide ...

Age is the biggest risk for heart disease, but lifestyle and meds have impact

December 12, 2018
Of all the risk factors for heart disease, age is the strongest predictor of potential trouble.

New understanding of mysterious 'hereditary swelling'

December 12, 2018
For the first time ever, biomedical researchers from Aarhus University, Denmark, report cellular defects that lead to a rare disease, hereditary angioedema (HAE), in which patients experience recurrent episodes of swelling ...

Macrophage cells key to helping heart repair—and potentially regenerate, new study finds

December 11, 2018
Scientists at the Peter Munk Cardiac Centre have identified the type of cell key to helping the heart repair and potentially regenerate following a heart attack.

Research team traces pathway to cardioprotection in post-ischemic heart failure

December 11, 2018
During an ischemic attack, the heart is temporarily robbed of its blood supply. The aftermath is devastating: reduced heart contractility, heart cell death, and heart failure. Contributing to these detrimental changes is ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.