The role of oxidative stress on cardiovascular diseases (CVD) is still the subject of studies. Oxidative stress, as a result of a significant increase in concetration of reactive oxygen species (ROS), leads to changes in vascular function such as endothelial dysfunction. Factors that promote endothelial dysfunction are associated with the development of CVD. It has been shown that an increased concentration of ROS such as \(O_{2}\)\( ^{-}\) leads to the formation of atherosclerotic plaques and a decrease in nitric oxide (NO) in atherosclerosis. Oxidative stress also causes left ventricular dilatation and contractile dysfunction of the heart muscle. In arterial hypertension, it has the effect of reducing the concentration of NO and increasing angiotensin II (Ang II). Various risk factors such as diabetes, smoking and polluted air promote oxidative stress. Particles of polluted air and cigarette smoke will reduce lung defense mechanisms and cause oxidative stress in most lung cell types. In addition, hyperglycemia a state typically occuring in diabetes, has also been shown to cause oxidative stress by glucose autooxidation and non-enzymatic glycosylation of proteins. For this reason, the effect of plant-based diet in the prevention of CVD has been increasingly studied. A Mediterranean diet, rich in polyphenols and flavonoids shows a particularly beneficial effect in reducing markers of oxidative stress.