A chemical found in red meat has been discovered which contributes to atherosclerosis, the hardening and clogging of arteries.
A Cleveland Clinic study published in the journal Nature Medicine this week reports the discovery of a new chemical which links heart disease with red meat. The chemical carnite, which is present in the meat, is metabolized by bacteria in our digestive tracts, turning it into trimethylamine-N-oxide (TMAO), which is a metabolite that the researchers previously linked to heart disease in 2011. As if to make it worse, diets with a high content of carnite promotes the growth of the bacteria which produces TMAO.
The study examined the carnite and TMAO levels among omnivores, vegetarians and vegans and examined medical data from over 2500 patients undergoing cardiac evaluation. In addition, they used lab mice to examine the effects of a carnite heavy diet. They found that the TMAO metabolite alters cholesterol on several levels, which is why it contributes to atherosclerosis.
Mmmm… Worth it anyway
The end result of high carnite intake, as revealed by the study, is that when converted into TMAO, there is an increased risk for severe heart related issues like heart attacks, strokes… even death. However, the carnite intake only has negative effects if the necessary gut microbes are in place to convert it to TMAO. As such, vegetarians and vegans eating large amounts of carnite did not experience the same rise in TMAO as omnivores did.
Research team leader Stanley Hanzen, M.D. Ph. D, explains: "The bacteria living in our digestive tracts are dictated by our long-term dietary patterns. A diet high in carnitine actually shifts our gut microbe composition to those that like carnitine, making meat eaters even more susceptible to forming TMAO and its artery-clogging effects. Meanwhile, vegans and vegetarians have a significantly reduced capacity to synthesize TMAO from carnitine, which may explain the cardiovascular health benefits of these diets."
Previous research has shown a link between heart issues and red meat consumption, but until now, the research has been unable to fully explain the link, since the fat and cholesterol content of red meat is not thought to be high enough to fully explain the effects. This new research may be the missing link.
Though carnite is naturally found in beef, pork, mutton, lamb, venison and duck, it is also found in diet supplement pills and in many energy drinks. "Carnitine is not an essential nutrient; our body naturally produces all we need," saysHanzen, "We need to examine the safety of chronically consuming carnitine supplements as we've shown that, under some conditions, it can foster the growth of bacteria that produce TMAO and potentially clog arteries.