Meat eaters increase the risk of atherosclerosis (hardening of the arteries) further if they also regularly have energy drinks, because they contain carnitine as well.
Bacteria in our guts metabolize carnitine into TMAO (trimethylamine-N-oxide), and people with high levels of TMAO are more likely to suffer from heart disease and stroke. And, just to complete the vicious circle, carnitine also produces more of the bacteria that create TMAO.
Researchers at the Cleveland Clinic made the discovery when they examined the records of 2,595 who were having heart tests. Vegetarians and vegans had far lower levels of TMAO-and they remained low even after they consumed high levels of carnitine, suggesting the problem is caused by a long-term diet of meat-eating.
On its own, the cholesterol and saturated fat content of red meat isn't enough to explain the increased heart risk, suggesting TMAO is the main culprit.
(Source: Nature Medicine, 2013; doi: 10.1038/nm.3145).