Ascorbic Acid and Atherosclerosis

Abstract

The role of ascorbic acid or vitamin C has been proposed in the prevention of atherosclerosis.The possibility is discussed that the antioxidant effect of ascorbic acid might be protective against and possibly propitious to atherosclerosis. Growing evidence suggests that oxidative modification of lowdensity lipoprotein (LDL) may be of particular importance in the pathogenesis of atherosclerosis because oxidized LDL exhibits proatherogenic effects. In addition to oxidative modification of LDL hypothesis, inflammatory process potentiated by cytokines also importantly contributes to the pathogenesis. These complex mechanisms presumably participate in endothelial injury resulting in impaired releasing factors, such as nitric oxide (NO) and prostanoids, taking part in abnormal vascular tone. Therefore, vasoactive substances produced from endothelium and their pathways may be modulated by both cytokines-and oxidized LDL-induced oxidative stress. Recently, antioxidants have been determined that can prevent LDL oxidation beneficial to the inhibition of atherosclerotic process.

There are accumulating experimental, epidemiological, and clinical evidences of an associationbetween antioxidant vitamin intake and reduced risk of coronary heart disease. In animal models, ascorbic acid has been shown to attenuate the oxidation of LDL and atherosclerotic lesions. Population studies suggest an inverse relationship between ascorbic intake and the development of atherosclerosis, although the effect has not yet been proven in clinical trials. A possible mechanism for the antiatherogeniceffect of ascorbic acid is the prevention of oxidation of LDL. Furthermore, the potential effects of ascorbic acid on the metabolism of NO and prostanoids as well as in the defense on monocyte adherence might particularly improve endothelial function in atherosclerosis. These finding should be pursued in basic research studies to elucidate its molecular biological mechanisms,additionally in clinical epidemiological studies of ascorbic supplementation in populations in order toverify a role of ascorbic acid for the practical use in clinical medicine.