Cleveland Clinic researchers show dietary choline and TMAO linked with increased blood clotting


EMBARGOED UNTIL 4 P.M. EST, MONDAY, APRIL 24, 2017Cleveland: Cleveland Clinic researchers have shown, for the first time in humans, that choline is directly linked to increased production of a gut bacteria byproduct that increases the risk of blood-clotting events like heart attack and stroke. However, the research also showed that adding a low dose of aspirin may reduce that risk.

In a small interventional study, the researchers provided oral choline supplements to groups of healthy vegans/vegetarians (eight patients) and omnivores (10 patients). Both groups showed at least a 10-fold increase in plasma levels of trimethylamine N-oxide (TMAO) – a metabolite generated by gut microbes ¬- after choline supplementation, as well as an increase in platelet responsiveness, a risk factor for thrombotic events (blood clotting) like heart attack and stroke.

In a separate study, omnivores not taking supplements initially had platelet function tested at baseline, and then after taking a daily regimen of low-dose aspirin for at least a month. They then were followed for another two months while continuing to take aspirin and a daily supplement of choline. The researchers found that while elevated TMAO levels and enhanced susceptibility for platelet activation still occurred, the TMAO levels were attenuated by aspirin. These new findings suggest two things – that a low dose of aspirin may partially counter the pro-thrombotic effects of a high TMAO plasma level associated with a Western diet rich in choline, commonly found in egg yolk and meats; and that a high TMAO level can partially overcome the beneficial anti-platelet effects of taking low dose aspirin.

The research team was led by Stanley Hazen, M.D., Ph.D., chair of the Department of Cellular & Molecular Medicine for the Lerner Research Institute and section head of Preventive Cardiology & Rehabilitation in the Miller Family Heart and Vascular Institute at Cleveland Clinic, and Dr Wilson Tang, cardiologist and transplant specialist at the Miller Family Heart and Vascular Institute at Cleveland Clinic. The research will be published April 24 in Circulation, the American Heart Association's journal, with Weifei Zhu, Ph.D., of Dr. Hazen's laboratory as lead author.

"This is the first study in humans to directly demonstrate that dietary choline substantially elevates TMAO production by gut bacteria, impacting platelet function. It provides direct evidence of a mechanistic link between TMAO levels and risk for blood clotting events like heart attack and stroke, the major culprit for the development of cardiovascular events," Dr. Hazen said. "Further research is necessary to confirm these findings, but these studies suggest patients without known cardiovascular disease but with elevated TMAO levels may benefit from aspirin and diet modification in preventing blood clotting, which can lead to heart attack and stroke. They also suggest that a high TMAO level in a patient with known cardiovascular disease should be considered for more aggressive anti-platelet therapy."

Dr. Hazen, who also holds the Jan Bleeksma Chair in Vascular Cell Biology and Atherosclerosis, has previously linked TMAO to an increased risk of cardiovascular disease and has shown it can be a powerful tool for predicting future heart attacks, stroke and death in multiple patient populations.

TMAO is a byproduct of bacterial digestion of choline, lecithin and carnitine, nutrients that are especially abundant in animal products such as red meat, processed meats and liver. In 2016, his team discovered in animal models that gut microbes alter platelet function and thrombosis risks, and that microbial transplantation studies could be used to demonstrate the TMAO pathway plays a role in thrombosis potential in a stroke model in mice. Findings from this new study shows that dietary choline in humans raises TMAO levels, which may directly alter platelet function, increasing thrombosis (blood clot) potential. These studies help explain the strong association between plasma TMAO levels and heart attack and stroke risk observed in a study of over 4000 patients.


This research was supported by grants from the National Institutes of Health and the Office of Dietary Supplements (R01HL103866, R01DK106000, R01HL126827).

About Cleveland Clinic

Cleveland Clinic is a nonprofit multispecialty academic medical center that integrates clinical and hospital care with research and education. Located in Cleveland, Ohio, it was founded in 1921 by four renowned physicians with a vision of providing outstanding patient care based upon the principles of cooperation, compassion and innovation. Cleveland Clinic has pioneered many medical breakthroughs, including coronary artery bypass surgery and the first face transplant in the United States. U.S. News & World Report consistently names Cleveland Clinic as one of the nation's best hospitals in its annual "America's Best Hospitals" survey. Among Cleveland Clinic's 51,000 employees are more than 3,500 full-time salaried physicians and researchers and 14,000 nurses, representing 140 medical specialties and subspecialties. Cleveland Clinic's health system includes a 165-acre main campus near downtown Cleveland, 10 regional hospitals, more than 150 northern Ohio outpatient locations – including 18 full-service family health centers and three health and wellness centers – and locations in Weston, Fla.; Las Vegas, Nev.; Toronto, Canada; Abu Dhabi, UAE; and London, England. In 2016, there were 7.1 million outpatient visits, 161,674 hospital admissions and 207,610 surgical cases throughout Cleveland Clinic's health system. Patients came for treatment from every state and 185 countries. Visit us at Follow us at News and resources available at

About the Lerner Research Institute

The Lerner Research Institute is home to Cleveland Clinic's laboratory, translational and clinical research. Its mission is to promote human health by investigating in the laboratory and the clinic the causes of disease and discovering novel approaches to prevention and treatments; to train the next generation of biomedical researchers; and to foster productive collaborations with those providing clinical care. Lerner researchers publish ~1,500 articles in peer-reviewed biomedical journals each year. Lerner's total annual research expenditure was $260 million in 2016 (with $140 million in competitive federal funding, placing Lerner in the top five research institutes in the nation in federal grant funding). Approximately 1,500 people (including approximately 200 principal investigators, 240 research fellows, and about 150 graduate students) in 12 departments work in research programs focusing on heart and vascular, cancer, brain, eye, metabolic, musculoskeletal, inflammatory and fibrotic diseases. The Lerner has more than 700,000 square feet of lab, office and scientific core services space. Lerner faculty oversee the curriculum and teach students enrolled in the Cleveland Clinic Lerner College of Medicine (CCLCM) of Case Western Reserve University – training the next generation of physician-scientists. Institute faculty also participate in multiple doctoral programs, including the Molecular Medicine PhD Program, which integrates traditional graduate training with an emphasis on human diseases. The Lerner is a significant source of commercial property, generating 64 invention disclosures, 15 licenses, 121 patents, and one new spinoff company in 2016. Visit us at Follow us on Twitter at

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Andrea Pacetti, 216.444.8168, [email protected]
Alicia Reale Cooney, 216.445.8324, [email protected]

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1 Comment
  1. Judith says

    I suffer from TMAU. What dosage of low dose aspirin should I take?

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