Link Between Red Meat and Heart Health Happens in the Gut, Study Finds

Frequent red meat eaters produce more of a compound called TMAO

For years we’ve been advised to go easy on the steak dinners, because research that has shown that diets low in red meat are healthiest for our hearts.

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Now, new research is continuing to uncover details about how a diet that includes too much red meat can impact our risk of heart disease, including heart attack and stroke. And it’s not just about fats and cholesterol.

It starts in the gut

Past research spearheaded by Stanley Hazen, MD, Chairman of the Department of Cellular and Molecular Medicine at Cleveland Clinic’s Lerner Research Institute, has established that bacteria in the gut is a key player in red meat’s effect on heart disease risk.

Gut bacteria produce a compound called trimethylamine N-oxide (TMAO) when they digests choline, lecithin and carnitine, which are nutrients that are abundant in animal products such as red meat and liver, as well as other animal products. High levels of circulating TMAO in the body have been shown to be a powerful tool for predicting future heart attack, stroke and death risk.

More red meat, more TMAO

Dr. Hazen’s latest study found a two- to three-fold increase in TMAO levels in participants who ate red meat as their primary source of protein (accounting for 25 percent of their daily calories) for one month, compared to participants who relied on either white meat or plant-based foods as their top sources of protein.

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The red meat diet delivered a double whammy effect – not only did the study participants who followed it produce more TMAO than those on the other diets, but their kidneys were also less efficient at eliminating the TMAO from the body.

However, after those participants stopped eating the high-red meat diet, their TMAO levels came back down to normal within three to four weeks. This indicates that TMAO levels are modifiable, meaning we can change our heart disease risk by making changes to our diet, Dr. Hazen says.

The study participants who got their protein from white meat or plant-based sources had lower gut microbe creation of TMAO and improved kidney elimination of TMAO, suggesting that these types of diets are healthier for our hearts and bodies, he adds.

“We know lifestyle factors are critical for cardiovascular health, and these findings build upon our previous research on TMAO’s link with heart disease,” Dr. Hazen says. “They provide further evidence for how dietary interventions may be an effective treatment strategy to reduce TMAO levels and lower subsequent risk of heart disease.”

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As researchers learn more about TMAO and how gut microbes create it from choline, carnitine and lecithin, it opens up the possibility of finding ways to interrupt that process in order to reduce a person’s risk for cardiovascular disease.

Dr. Hazen explains, “We can use a TMAO level to help personalize dietary choices in an individual to help identify, for a given person, how much red meat is too much, and how to try to chase after lowering the level, much in the same way we do with cholesterol levels or triglyceride levels or glucose levels.”

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