A new study purports to demonstrate that the reason consumption of red meat seems to increase the risk of heart disease is not due to the presence of saturated fat and cholesterol.
One is tempted to say, “Duh!”
However, the “answer” creates more confusion than clarity, as the culprit is carnitine, a biological compound synthesized from the amino acids found in meat. Carnitine is essential to the transport of fatty acids inside cells, where they are metabolized for energy production.
Cleveland Clinic researchers identified a bacteria in the intestinal tract that interact with carnitine and turns it trimethylamine-N-oxide (TMAO), a metabolic waste product linked to the promotion of atherosclerosis, a disease where plaque builds up in arteries, compromising the circulation of oxygenated blood to the heart and other internal organs. Atherosclerosis is considered a serious risk factor for heart attacks and strokes.
“Carnitine metabolism suggests a new way to help explain why a diet rich in red meat promotes atherosclerosis,” Dr. Stanley Hazen stated in a Cleveland Clinic news release. Hazen is section head of preventive cardiology and rehabilitation in the Miller Family Heart and Vascular Institute at the Cleveland Clinic and the lead author of the study, which was published in the April 7 issue of Nature Medicine online.
According to the news release, Hazen and his team determined that not only do intestinal bacteria turn carnitine into TMAO, but a diet high in carnitine promotes the growth of those carnitine metabolizing bacteria, creating a vicious cycle.
The study was based on evaluations of 2,595 patients undergoing heart exams, and the data showed that increased carnitine levels raised the risks for cardiac events in subjects with high levels of TMAO.
What’s even worse, however (if you only read the clinic’s news release), the researchers found that the baseline TMAO levels were significantly lower among vegans and vegetarians, as opposed to omnivores. Even after consuming a large amount of carnitine, vegans and vegetarians did not produce significant levels of TMAO, whereas omnivores consuming the same amount of carnitine did.
“A diet high in carnitine actually shifts our gut microbe composition to those that like carnitine,” Hazen said, “making meat eaters even more susceptible to forming TMAO and its artery-clogging effects.”
A multi-faceted Rx
Okay, so it’s obvious, right? Less meat means less carnitine, which means less obnoxious gut bacteria producing waste products that turn your arteries into clogged sludge.