New Discovery on Heart Disease has Scientists Seeing Red

As the height of summer approaches, dinnertime could have you dreaming of barbeque season. But a recent Nature Medicine study[i] might persuade you to reconsider that burger.

Doctors and scientists have known for a long time that red meat should be enjoyed sparingly for a healthy heart. We recognize fruits and veggies as allies in the national battle against heart disease, and know the benefits of lean protein. Yet it has long been a mystery why people with high levels of cholesterol sometimes never develop heart disease, while those with moderate levels can suffer an attack early on.

The answer may be a buggy one. New research indicates our gut bacteria are good students: if we consume red meat- and its chemical compound, L-Carnitine- frequently, our microbes learn to enjoy it as well. In processing the compound, they expel a by-product called TMAO, which signals atherosclerosis  (inflammation and thickening of the arteries) in large quantities, potentially causing a heart attack.

The study was composed of both omnivores who reported eating red meat frequently, and vegans/vegetarians who had not eaten meat in at least a year’s time.

Beef-buffs demonstrated high levels of potentially dangerous TMAO, while vegans/vegetarian levels were negligible. To ensure this was indeed microbe-related, scientists put 5 omnivores on a regimen of antibiotics to curb this microbial feeding frenzy before repeating the experiment. Results were astounding. In the second go-around, the 5 supplemented omnivores had nearly non-existent levels of TMAO! Apparently, vegans/vegetarians are unable to produce dangerous levels of the by-product, because they have a different ecosystem of microbes in their gut.

Another study recently published in the New England Journal of Medicine found similar findings when people consumed choline in the form of lecithin (found in eggs) ii.

These studies  shed light on the influence of animal protein on heart attack risk (independent from cholesterol levels.)  Additionally, these studies add to the growing knowledge of the importance of gut bacteria to our health.  No doubt, future research will focus on identifying which strains of healthy bacteria (Probiotics) to give people in order to push out those producing TMAO, thereby reduce the risk of heart disease for meat eaters.

In the meantime, this research confirms my long-standing recommendation that taking medication or dietary supplements to lower cholesterol does not give you permission to eat as much red meat as you’d like.  I recommend investigating beef-alternatives for your next cookout:  Vegetable or fish patties are great options that blend right in with other classic summer foods like watermelon, seasonal tomatoes, and burger condiments.

Wishing you good health and happiness!


P.S. You may have seen L-Carnitine supplements promoting muscle definition at your local GMC. Interestingly enough, the human body produces enough L-Carnitine on its own, even in vegetarians and vegans.



i. Koeth, Robert A., Et Al. “Intestinal Microbiota Metabolism of L-Carnitine, a Nutrient in Red Meat, Promotes Atherosclerosis.” Nature Medicine 576th ser. 19.5 (2013): n. pag. Nature Publishing Group, May 2013. Web. 5 June 2013.

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