Trimethylamine N oxide (TMAO) is a small molecule produced in humans primarily by the gut liver axis and has become an important biomarker, and possible mediator, of cardiometabolic and renal disease. Dietary choline, phosphatidylcholine ( Trimethylamine N Oxide, More Red Meat for the Vascular Scientists Hypertension Decoding TMAO in the Gut Organ Axis: From Biomarkers and Cell Death Me DDDT Dove Medical Press Intestinal microbiota metabolism of l carnitine, a nutrient in red meat, promotes atherosclerosis Nature Medicine Gut microbiota metabolism of l carnitine and cardiovascular risk Atherosclerosis