Antioxidants

About the Auther

I. Statins
II. Vitamin E
III. Vitamin C
IV. Beta-Carotene
V. Mediterranean Diet
VI. Dietary Plant-Derived Flavonoids
VII. French Red Wine
VIII. Probucol

GLOSSARY
atherosclerosis same as atheroma, raised plaques filled with cholesterol, calcium, and other substances on the inner wall of arteries that obstruct the flow of blood; the plaque of atheroma hardens the artery, hence the term atherosclerosis (sclerosis ¼ hardening).
cardioprotection protection of the heart from serious events that include coronary artery disease and its complications, angina, myocardial infarction, and heart failure.
flavonoid any of a large group of crystalline compounds found in plants.
myocardial infarction death of an area of heart muscle due to blockage of a coronary artery by blood and atheroma; medical term for a heart attack or coronary thrombosis.
STEINBERG ET AL. WERE AMONG THE FIRST TO indicate that modified low-density lipoprotein (LDL) cholesterol could be responsible for the accumulation of lipid within macrophages, a crucial step in the early formation of atheromatous plaques.
Only some antioxidants prevent the oxidation of LDL cholesterol, which plays an important role in the pathogenesis of the atherosclerotic process and its pro¬gression to blockage of arteries (see the chapter Athero-sclerosis/Atherothrombosis). The harmful effect of LDL cholesterol is augmented by oxidized LDL cholesterol particles. Prevention of the oxidation of LDL cholesterol particles by chemical agents and natural products is an area of intensive research. Natural substances and chemical compounds, which may protect lipids from attack by oxygen free radicals increase resistance to lipid peroxida-tion, reverse endothelial dysfunction, and increase nitric oxide (NO) mediated vasodilation will remain an inter¬esting area of research and development, despite the negative results observed in many clinical trials.

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  • I. STATINS
    Statins are well-known, cholesterol-lowering agents. They are competitive inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, which is the key enzyme catabolizing the early rate-limiting step in the bio¬synthesis of cholesterol within the hepatocyte. They lower LDL cholesterol in blood and thus prevent heart attacks and death from myocardial infarction as well as strokes. More important, statins have been shown to prevent lipo-protein oxidation, and it is believed that some of their salutary effects may be related to this action. They appear to improve survival in patients with ischemic and non-ischemic heart failure. Nitric oxide synthesis is diminished in heart failure; statins enhance endothelial NO synthase (eNOS) activity and improve endothelial function (see the section Statins in the Dyslipidemia chapter).
  • II. VITAMIN E
    Antioxidant nutrients, particularly vitamin E, are still widely used with the hope of preventing cancer, heart disease, and dementia. Although, clinical trials have not shown protection from cancer, the correct ‘‘protective’’ dose may not have been used in some trials. Also, the partially favorable effect of vitamin E on amyloid depo¬sition in the brain and its effect on dementia remains to be clarified.
  • III. VITAMIN C
    Although vitamin C, ascorbic acid, is one of the most important antioxidants in extracellular fluids, it traps peroxyl radicals and inhibits lipid peroxidation. Several studies indicate that there is no apparent benefit in the prevention of cardiovascular disease with use of vitamin C.
  • IV. BETA-CAROTENE
    Results of several clinical trials indicated that beta-carotene supplementation is not beneficial in the prevention of cardiovascular disease or its complications.
  • V. MEDITERRANEAN DIET
    The Mediterranean diet contains a substantial amount of antioxidants and has been shown to be substantially cardioprotective. However, there are many other cardio-protective facets in this diet, including an abundance of beneficial alpha-linolenic acid (see the chapter Diets and Heart Disease).
  • VI. DIETARY PLANT-DERIVED FLAVONOIDS
    These naturally derived products from several sources including red grape juice, red wine, soy products, and nuts (particularly almonds, walnuts, and hazel nuts), are receiving attention for their antioxidant and cardioprotec-tive properties.
  • VII. FRENCH RED WINE
    French red wine appears to be more cardioprotective than wine from other countries. Although the data for differences in red and white wine remain controversial, and it appears that all alcoholic beverages carry some cardioprotective properties, it seems that French red wine possesses further cardioprotective properties.
  • VIII. PROBUCOL
    Two small studies have demonstrated that probucol, a drug used in the 1970s for lowering serum cholesterol, which was abandoned because of adverse effects, has important additional antioxidant properties. Probucol significantly reduces restenosis when administered one month before and continued for six months after percutaneous trans-luminal coronary angioplasty (PTCA). The small group, 317 patients, used in these studies limits the conclusions regarding the benefits of this drug.
  • BIBLIOGRAPHY
    Appeldoorn, C. C. M., Bonnefoy, A., Bianca, C. H. et al. Gallic acid antagonizes P-Selectin – mediated platelet – leukocyte interactions: Implications for the French paradox. Circulation, 111:106–112, 2005.