Chemical in Red Meat Is Linked to Heart Disease

By Jane Farrell

Yet another reason to limit consumption of red meat: It contains high levels of a chemical called trimethylamine N-oxide (TMAO), that also is linked to heart disease.

People who eat a diet high in red meat have triple the TMAO levels of those who eat a diet rich in white meat or mostly plant-based proteins, a study has found. The good news is that giving up red meat eventually lowers those TMAO levels.

Tracking  individuals’ TMAO levels could be an important step toward using personalized medicine to fight heart disease.

TMAO is a dietary byproduct that is formed by gut bacteria during digestion and is derived in part from nutrients that are abundant in red meat. While high saturated fat levels in red meat have long been known to contribute to heart disease—the leading cause of death in the United States—a growing number of studies have identified TMAO as another culprit. Until now, researchers knew little about how typical dietary patterns influence TMAO production or elimination.

The researchers’ conclusion suggest that measuring and targeting TMAO levels—something doctors can do with a simple blood test—may be a promising new strategy for individualizing diets and helping to prevent heart disease.

The study was funded largely by the National Heart, Lung, and Blood Institute (NHLBI), part of the National Institutes of Health. It was published in the European Heart Journal, a publication of the European Society of Cardiology.

“These findings reinforce current dietary recommendations that encourage all ages to follow a heart-healthy eating plan that limits red meat,” said Charlotte Pratt, Ph.D., the NHLBI project officer for the study and a nutrition researcher and Deputy Chief of the Clinical Applications & Prevention Branch, Division of Cardiovascular Sciences, NHLBI. “This means eating a variety of foods, including more vegetables, fruits, whole grains, low-fat dairy foods, and plant-based protein sources such as beans and peas.”

“This study shows for the first time what a dramatic effect changing your diet has on levels of TMAO, which is increasingly linked to heart disease,” said Stanley L. Hazen, M.D., Ph.D., senior author of the study and section head of Preventive Cardiology & Rehabilitation at the Cleveland Clinic. “It suggests that you can lower your heart disease risk by lowering TMAO.”

Hazen estimated that as many as a quarter of middle-aged Americans have naturally elevated TMAO levels, which are made worse by chronic red meat consumption. However, every person’s TMAO profile appears to be different, so tracking this chemical marker, Hazen suggested, could be an important step in using personalized medicine to fight heart disease.