JCI l Carnitine in omnivorous diets induces an atherogenic gut microbial pathway in humans TMAO: The Gut Metabolite Linking Red Meat to Cardiovascular Disease L carnitine is primarily synthesized in the liver from the amino acids lysine and methionine through a series of four enzymatic reactions, with the liver and kidneys converting the precursor butyrobetaine into active Comparison of short term and long term effects of peroral L carnitine intake: clinical implications of elevated TMAO levels in cardiovascular complications L Carnitine Side Effects & Risks