Intestinal microbiota metabolism of l carnitine, a nutrient in red meat, promotes atherosclerosis Acetyl L Carnitine MRM Nutrition Characterization of TMAO productivity from carnitine challenge facilitates personalized nutrition and microbiome signatures discovery Microbiome Springer Nature Link The Role of Gut Microbiota Derived Trimethylamine N Oxide in the Pathogenesis and Treatment of Mild Cognitive Impairment