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May 06, 2013

Compound in Red Meat Linked to Heart Disease

Carnitine, found in red meats and energy drinks, may increase heart disease risk.

Fat and cholesterol may not be the only reason we should limit our intake of red meat, according to a recent study published in the medical journal, Nature Medicine. Researchers at the Cleveland Clinic have identified a substance contained in red meat called carnitine that may indirectly cause our arteries to harden, leading to heart disease.

This study included nearly 2,600 patients with diets that ranged from regular red meat eaters to vegetarians and vegans. After conducting heart evaluations on study participants, investigators found an interesting chain reaction that takes place as meats are digested by the body, which could negatively impact heart health. Compared to vegetarians and vegans, meat eaters had significantly higher levels of a chemical called TMAO, which gets into the blood and increases heart disease risk. Upon further investigation, researchers found that the carnitine contained in red meat is broken down into TMAO by a specific type of bacteria which is more common in meat eaters vs. vegetarians. So, if a vegetarian tries red meat, their TMAO levels don’t spike because they don’t have the bacteria that converts carnitine into these harmful compounds. However, TMAO levels increase after a meat eater ingests red meat, increasing the negative effects of the compound. Interestingly, researchers also found that when meat eaters cleared their bodies of this certain bacteria, their TMAO levels remained low even after ingesting red meat.

While these findings are enlightening to experts, they raise both questions and concerns. First, researchers wonder if reducing carnitine or eliminating the bacteria that digests carnitine could lower TMAO levels, thus lowering risk for heart disease. Although this study shows an association between carnitine and TMAO levels, it’s not clear whether there’s a cause and effect relationship between carnitine and heart disease. Experts also wonder if high TMAO levels should be considered a risk factor for heart disease, and whether or not people with higher TMAO levels should take steps to lower these levels. Perhaps most alarming, however, is the fact that carnitine is actually added to energy drinks to help increase energy levels and boost metabolism. Could the carnitine contained in energy drinks also be harmful for our hearts? More research is needed to fully understand how carnitine may impact heart health, but it’s safe to say that our understanding of a balanced, heart-healthy balanced diet remains the same. To promote better heart health, we should still limit red meats and try to fill our meals with lean proteins, like chicken and fish, along with plenty of vegetables and whole grains.

Questions for You to Consider

  • Is red meat bad for my heart?
  • Red meat contains high levels of fat and cholesterol, which can clog our arteries and increase risk for heart disease. Research also suggests that a substance contained in red meat, called carnitine, may increase levels of the chemical TMAO, which increases cardiovascular risk. To promote heart health, it’s important to limit consumption of red meat to once a week or less and maintain a balanced diet full of lean protein, fresh vegetables and whole grains.
  • How often should I eat red meat?
  • In general, red meat should be consumed rarely—about one serving a week or less. Although protein is an important part of a balanced diet, lean meats, fish and nuts are a better choice than red meat to promote heart health.


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