THE ANTIOXIDANT VITAMINS - IMPACT ON ATHEROSCLEROSIS

Atherosclerosis, the great killer of Western society, probably is init iated when the balance of subendothelial lipoproteins and oxidation po tential is upset. Oxidation products, especially oxidized low-density lipoprotein, set into motion the cascading of numerous pathways, culmi nating in the fibrous atherosclerotic plaque. The natural antioxidant system includes enzymes and vitamins A, E, and C. The lipophilic-vitam ins A and E protect the fatty acid components of lipoproteins and memb ranes, and vitamin C functions in the aqueous phase both directly and by regenerating oxidized vitamin E. In animal models, the antioxidant vitamins protect lipids and prevent atherosclerosis. Population studie s suggest an inverse relationship between atherosclerosis and vitamin levels. Several observational studies and some clinical trials have de monstrated that antioxidant vitamin supplements may prevent atheroscle rosis. Although approximately 20% of the United States population regu larly consumes vitamin supplements, often in high doses, the antiather ogenic benefits of antioxidant vitamins remain unproved by clinical tr ials, and the long-term effects of megadose vitamins are yet undefined .