But there is a way to reverse the effects.

By Lauren Wicks
Updated December 11, 2018
Getty: Roxiller

New research is giving us yet another reason to limit red meat consumption: its impact on heart disease risk. A study conducted by the National Heart, Lung, and Blood Institute (published in the European Heart Journal) found that both heart and gut health is impacted by a chemical called trimethylamine N-oxide (also known as TMAO)—which is a chemical byproduct derived in part from nutrients found in red meat.

Scientists discovered those who eat a diet rich in red meat have three times the TMAO levels compared to those who eat mostly white meat or plant-based protein sources. But the research also found that high TMAO levels can be reversed by replacing red meat with increased white meat or plant-based proteins.

“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., in  a press release. Hazen is the senior author of the study and a Preventive Cardiology & Rehabilitation section head at the Cleveland Clinic.

Hazen noted as many as a quarter of Americans have naturally elevated TMAO levels, which are made worse by excessive red meat consumption. The study suggests that measuring and targeting TMAO levels—which can be done with a simple blood test—could be a promising way to prevent heart disease, along with individualized diet plans.

The study examined 113 healthy men and women by having them follow a standard American diet—49 percent of their calories came from carbohydrates, 14 percent from protein, and 37 percent from fat for a period of two weeks. Participants were then randomly placed on a variety of diets based on varying protein consumption, and were expected to obtain 25 percent of their calories from protein each day.

One group ate a diet heavily based in red meat for protein, whereas another consumed mostly white meat, and the third ate mostly plant-based protein sources. From there, half of each group were put on a high-fat diet so that the effects of each protein source on TMAO were independent of dietary fat intake.

Easy recipes to incorporate more plant-based protein into your diet:

The red meat-centric diet allowed for participants to eat about eight ounces daily, either a steak or two quarter-pound beef patties. After one month, researchers found, on average, blood levels of TMAO in these participants tripled in comparison to those eating diets rich in white meat or non-meat protein sources.

The good news? It only took four weeks to reduce high TMAO levels after discontinuing red meat consumption.

“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., a nutrition researcher at the National Heart, Lung, and Blood Institute. “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.”  

How exactly TMAO affects heart disease is still unclear. Research has shown TMAO can affect cholesterol deposits on the artery wall, creating “clogged arteries.” TMAO has also been shown to interact with platelets in a way that can lead to clotting-related activities, including heart attack and stroke.