Antioxidant vitamins in atherosclerosis--animal experiments and clinical studies.

Atherosclerotic heart diseases are universal problems in modern society. Oxidative damage to lipids is a primary cause of atherosclerosis. There are many choices for treatment, but no definite recommendations to prevent the occurrence of the disease. There is a relationship between atherosclerotic risk factors and increased vascular production of reactive oxygen species (ROS). Oxidized low-density lipoproteins (LDL) and ROS may directly cause endothelial dysfunction by reducing endothelial nitric oxide (NO) bioavailability. Vitamin E can to some degree prevent the consequences of oxidized LDL, and vitamin C provides NO synthase activity. Although prolonged use of vitamin A, C, and E supplementation in pharmaceutical forms has been proven to be effective in preventing atherosclerosis in animal experiments, this has not yet been demonstrated in clinical trials with human beings. It should be taken into account that the evidence has been gathered from young/adult experimental animals with early stages of arthrosclerosis and from in-vitro studies, while most of the clinical trials have involved older patients with late stages of the disease. Prolonged use of vitamins in the diet has not yet been recommended in human beings. There is some indication that a diet rich in antioxidant fruit and vegetables may be beneficial in the prevention of cardiovascular events.