L-CARNITINE ↑ TMAO a toxic substance formed when one eats beef, red meat, meatballs, meatloaf; ↑ risk ASHD, changes gut flora, ↑ heart disease. Plasma L-carnitine levels in subjects undergoing cardiac evaluation predicted ↑ risks for both prevalent cardiovascular disease & cardiac events (myocardial infarction, stroke or death), only appeared among subjects with ↑ TMAO (trimethylamine N-oxide) levels.