Another reason to embrace Meatless Monday

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Meatless Monday just gained a little more clout. A recent science report suggests that increased levels of a compound called tremethlyamine N-oxide (TMAO) that’s made in the gut, is associated with heart disease. Researchers discovered that people who consume a lot of red meat have three times the TMAO levels compared to those who eat a diet containing mostly white meat or plant-based proteins. Stopping red meat consumption can reverse the effect and reduce TMAO levels. 1

Gut bacteria creates TMAO during digestion as a byproduct of the nutrients found in red meat. Saturated fat has previously been identified as a contributor to heart disease, but more and more studies have linked TMAO as another felon. Researchers did not know much about how dietary patterns affected TMAO creation or elimination until now. 1

The research suggests that measuring and focusing on TMAO levels may be something doctors can perform as a new way to individualize diets to help prevent heart disease. The National Heart, Lung, and Blood Institute (part of the NIH) largely funded the study which was published on Dec. 10 in the European Heart Journal, a publication of the European Society of Cardiology. 1

According to Charlotte Pratt, PhD, the NHLBI project officer for the study and nutrition scientist and Deputy Chief of the Clinical Applications and Prevention Branch Division of Cardiovascular Sciences, NHLBI, "These findings reinforce current dietary recommendations that encourage all ages to follow a heart-healthy eating plan that limits red meat," "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." 1

"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." 1

By Hazen’s estimates, as much as 25% of middle-aged Americans have naturally high TMAO levels, which are worsened by chronic intake of red meat. But, every person’s TMAO levels vary, so following the chemical marker could be a novel way to use personalized medicine to prevent heart disease, according to Hazen. 1

For the research, scientists had 113 healthy men and women as participants in the clinical trial to look at the effects of dietary protein from red meat, white meat and plant-based sources on TMAO production.  In random order, all participants were advised to follow each diet for a month. During the red meat diet, subjects ate approximately 8 oz. of steak daily or two quarter pound beef patties. Researchers noted that after one month, on average, TMAO levels in the blood of these participants had tripled versus when they followed the diets containing either white meat or plant-based protein sources. 1

Each study diet provided about the same number of calories, but half of the participants were advised to eat high-fat versions of the three diets, and scientists found similar results. Therefore, the impact of the source of protein on TMAO levels were independent of fat consumption. 1

Of note, the scientists found that increased TMAO levels were reversible and significantly dropped when the subjects stopped consuming red meat and went to either a diet containing white meat or plant-based protein for another month. 1

The way in which TMAO impacts heart disease is complicated. Previous studies have found that TMAO exacerbates cholesterol deposition in the cells of arterial walls. Research studies also hint that TMAO interacts with platelets, blood cells needed for normal clotting function, in that they increase the chance for clot-related events like heart attack and stroke. 1

Hazen’s lab developed a quick, simple blood test to test TMAO levels which is available to consumers. He and his colleagues have reportedly developed drugs to reduce TMAO levels, reduce atherosclerosis and risk of clotting which are in the experimental stage in animal models and not publicly available. 1

Here are 5 easy ways your clients can keep TMAO levels low:

  1. Start with Meatless Mondays. This is an easy way to initiate plant-based meals.
  2. Swap ground beef for ground turkey in meatloaf, tacos, spaghetti and other dishes. Choose 90% lean or higher for lowest fat content.
  3. Choose grilled and broiled fish when eating out. Or consider a vegetarian option!
  4. Delete half or all of the meat in chili and use beans instead.
  5. Make the switch to veggie or bean patties in place of beef burgers. Your heart will thank you in the long run. And many of the options in the store taste really great! Plus they are easy to make!

Download PDF Printable Handout: 5 Ways to Meatless Meals


  1. Zeneng Wang et al. Impact of chronic dietary red meat, white meat, or non-meat protein on trimethylamine N-oxide metabolism and renal excretion in healthy men and womenEuropean Heart Journal, 2018 DOI: 1093/eurheartj/ehy799

Submitted by Lisa Andrews, MEd, RD, LD

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