We’re humans. We’re naturally omnivores. So why are health experts always trying to get us to lay off of meat? It’s the vegetarians—and especially vegans—who are the unnatural ones, right? Well, maybe in some ways, but results of a new study indicate they may have the last laugh… literally… since we omnivores will be dead from heart disease.

Researchers from the Cleveland Clinic believe carnitine, a compound found in red meat—and many popular energy drinks—promotes hardening and clogging of the arteries, also known as atherosclerosis. They say bacteria naturally occurring in the digestive tract convert carnitine into the chemical trimethylamine-N-oxide—TMAO. Previous research from the sale clinic found TMAO promotes atherosclerosis. But the new study also found that a diet high in carnitine actually promote the growth of the bacteria that metabolize it, resulting in even higher TMAO production.

“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,” study leader Dr. Stanley Hazen, head of preventive cardiology and rehabilitation in Cleveland Clinic’s Heart and Vascular Institute, said in a clinic news release.

Cleveland Clinic researcher studied almost 2,600 patients undergoing routine heart evaluations. They found higher carnitine levels were consistently associated with higher risks of heart disease, heart attacks, strokes and other heart-related deaths.

But TMAO levels in vegetarians and vegans were not only lower than in omnivores, they did not produce significant levels of TMAO even after consuming a large amount of carnitine.

While the study recognizes it can’t exactly prove a cause-effect relationship between carnitine and heart damage, researchers believe the findings provide a new understanding of the benefits of vegan and vegetarian diets.

“Vegans and vegetarians have a significantly reduced capacity to synthesize TMAO from carnitine, which may explain the cardiovascular health benefits of these diets,” Hazen said.