A randomized controlled feeding trial published in the
European Heart Journal found that red meat consumption is more likely to lead to atherosclerosis (hardening of the arteries) than the consumption of white meat or plant proteins. One hundred and thirteen healthy adult volunteers ate specially prepared meals for three four-week periods. One diet was based on red meat protein sources, the second got its protein from white meat, and the third provided plant proteins.
Proteins contain nutrients called choline and carnitine. Gut microbes convert these nutrients into trimethylamine (TMA), which the liver then coverts to trimethylamine N-oxide (TMAO). TMAO has been linked to the development of atherosclerotic heart disease. High blood levels of TMAO have been observed in people at risk for heart attack and stroke. Red meat has higher levels of carnitine than other protein sources and is also high in choline. High intake of red meat, therefore, supplies more raw materials from which the body makes TMAO.
This study found that consuming red meat increased plasma levels of TMAO. The good news is that discontinuing dietary red meat decreased TMAO levels within four weeks.