Don’t have a cow, man! ~ American cartoon character Bart Simpson
Modern production practices make an unhealthy food worse. Most beef cattle are given hormones to boost growth and build muscles. Most of these hormones remain in muscle tissue and are eaten by consumers.
Meat preparation presents a dilemma. Raw meat is a happy home for bacteria and other pathogens that can infect its consumer. Cooking meat, particularly at high temperatures, generates known carcinogens.
That eating red meat engenders cardiovascular disease is long known. The tasty fat marbled in the meat has long been pointed to as the villain, as has cholesterol. Those turn out be a subplot in the story, though consuming animal fat is unhealthy, and the wrong kind of cholesterol does damage.
Instead, carnitine is the culprit. The term carnitine derives from the Latin word carnis, meaning “the root of carnivore.” Red meat contains ample carnitine. Chicken, dairy products, fish, most body-building protein supplements, and energy drinks also have carnitine, albeit in smaller amounts.
Carnitine gets metabolized by the gut flora that perform most of human digestion. These bacteria burp a byproduct that turns into tmao (trimethylamine N-oxide) in the liver. tmao then travels through the circulatory system, facilitating cardiovascular disease. Elevated tmao levels correlate well with heart attack risk.
Vegans don’t have this problem. Their tmao levels are low. Even if they swallow pills with carnitine or have a steak (solely in the interest of research), their microbiota are healthier and so produce little to no tmao.
Current theory is that tmao enables cholesterol to wedge in artery walls, as well as preventing the body from properly regulating blood cholesterol level.