Advances in Clinical and Experimental Medicine 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 ( Simultaneous quantification of trimethylamine oxide and its precursors from gut microbial metabolic pathway Intestinal microbiota metabolism of l carnitine, a nutrient in red meat, promotes atherosclerosis Nature Medicine