Antioxidant vitamins and blood pressure.

Synthesis of free radicals might play a role in the cellular process of atherosclerosis. This process can be stopped by antioxidants such as beta-carotene, vitamin C, or vitamin E, which will inactivate the effects of free radicals. Although antioxidant vitamins have not been proven to prevent cardiovascular diseases through the modulation of lipid peroxidation, it has been suggested that peroxidation might be a pathway to such prevention, mediated through the effects of antioxidants on blood pressure (BP) and arterial stiffness. Several observational epidemiologic studies and some clinical trials have suggested an inverse association between dietary intake of fruits and vegetables, and BP. An inverse link between serum levels of vitamin C and BP has also been determined in observational epidemiologic settings. Some relations between other antioxidant vitamins (retinol and beta-carotene) and BP are reported; they confer the same inverse association. However, results from clinical trials testing the effect of a single, or a combination of antioxidants at high pharmacologic doses have revealed inconsistent BP findings. So far, no evidence confirms that oral antioxidant supplementation is effective in preventing or treating high BP. Additional large studies should be conducted to determine the effect on BP of antioxidant supplementation at nutritional doses.