It is well accepted that unbalanced ROS production actively participate in alterations of vascular tone associated with various diseases, such as hypertension, diabetes or atherosclerosis.33, 45 The major sources of ROS at vascular level are NADPH oxidase and mitochondria.46, 47, 48 Our data show for the first time that BCAA produce functional effects on the vascular wall. This evidence concerns the gene FMO5 and atherosclerosis.