Studies have found associations between red meat and heart disease, but exactly why the popular foodstuff can be harmful has been unexplained. A new study published earlier this week (April 7) in Nature Medicine suggests that a molecule found in steaks called L-carnitine is at fault. Gut bacteria convert it into trimethylamine N-oxide (TMAO), a molecule linked with arterial clogging, ScienceNOW reported.
The researchers found that after eating steak, human research subjects had elevated levels of TMAO. When some volunteers took antibiotics for a week and then the researchers gave them steak again, subjects’ blood TMAO levels were extremely low. Finally, feeding mice L-carnitine supplements, the researchers found that the animals’ TMAO levels soared, and their atherosclerosis levels doubled, but only if they had their full complement of gut bacteria.