Deep in the bowels of meat eaters live bacteria that gobble up a natural compound called L-carnitine and turn it into TMAO, a substance linked to clogged arteries. Red meat is rich in L-carnitine, and after eating a steak or taking an L-carnitine supplement, TMAO levels soar in people who eat meat. This does not happen to vegetarians, who don’t carry the same kinds of gut microbes. While the link between TMAO and heart disease remains unproved, it’s probably a good idea for people who eat red meat to avoid L-carnitine supplements.
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