High cholesterol level is not a major cause of coronary heart disease
Different from other people's opinion that high cholesterol is the major cause coronary heart disease, there are many research result that will lead us to have another opinion. Coronary heart disease is caused mainly by atherosclerosis. Some of us think that high cholesterol level will lead to building blockage in the blood vessel. Many people had a low cholesterol level (may be because of the cholesterol lowering drugs) but still got the coronary heart disease. On the other side, there are many people had a high cholesterol level, but they do not get the disease.
Atherosclerosis
Atherosclerosis is a disease affecting arterial blood vessels. It is commonly referred to as a "hardening" or "furring" of the arteries. It is caused by the formation of multiple plaques within the arteries, known as coronary heart disease.
Atherosclerosis is a condition where the walls of the arteries are damaged and narrowed by deposits of plaque (cholesterol and other fatty substances, calcium, fibrin, and cellular wastes), eventually blocking off the flow of blood. Plaque deposits can result in bleeding (hemorrhage) or formation of a blood clot (thrombus). When hemorrhage or thrombus blocks the flow of blood through the entire artery, a heart attack or a stroke occurs. High cholesterol levels - particularly the cholesterol carried by low-density lipoprotein ("LDL", a protein found in blood) - are associated with an increased risk of atherosclerosis. But LDL by itself is not dangerous, read the fact about oxidized LDL in this article.
Lipoprotein (a) is still a mystery
Studies have identified Lipoprotein (a) as a putative risk factor for atherosclerotic diseases as coronary heart disease and stroke. Lipoprotein (a) concentrations vary over one thousand fold between individuals, from 200 mg/dL. This range of concentrations is observed in all populations studied so far. The mean and median concentrations between different world populations show distinct particularities, the main being the two- to threefold higher Lipoprotein (a) plasma concentration of populations of African descent compared to Asian, Oceanic, or European populations.
High Lipoprotein (a) in blood is a risk factor for coronary heart disease (CHD), cerebrovascular disease (CVD), atherosclerosis, thrombosis, and stroke. Lipoprotein (a) concentrations may be affected by disease states, but are only slightly affected by diet, exercise, and other environmental factors. Commonly prescribed high cholesterol-reducing drugs have little or no effect on Lipoprotein (a) concentration. Niacin (nicotinic acid) and aspirin are two relatively safe, easily available, and inexpensive drugs known to significantly reduce the levels of Lipoprotein (a) in some individuals with high Lipoprotein (a); they should be used under the supervision of a qualified physician.
High Lipoprotein (a) predicts risk of early atherosclerosis similar to high LDL, but in advanced atherosclerosis, Lipoprotein (a) is an independent risk factor not dependent on LDL. High Cholesterol level do not have correlation with Lipoprotein (a) level.
Oxidized LDL
Normal LDL in plasma is not oxidized. Oxidation of LDL is believed to contribute to the development of atherosclerosis. Macrophage cells preferentially take up oxidized LDL, become loaded with lipids, and convert into foam cells. Foam cells accumulate in fatty streaks, early signs of atherosclerosis and leading to heart disease. Humans produce autoantibody against oxidized LDL, and the levels of such autoantibody are higher in patients with atherosclerosis. The identification of LDL oxidation as a key event in atherosclerosis suggests that it may be possible to reduce the risk of atherosclerosis by antioxidant supplementation. Vitamin E is the major naturally occurring antioxidant in human lipoproteins
Antioxidant
An antioxidant is a molecule capable of slowing or preventing the oxidation of other molecules. Oxidation is a chemical reaction that transfers electrons from a substance to an oxidizing agent. Oxidation reactions can produce free radicals, which start chain reactions that damage cells. Antioxidants terminate these chain reactions by removing free radical intermediates, and inhibit other oxidation reactions by being oxidized themselves. As a result, antioxidants are often reducing agents such as thiols or polyphenols.
Although oxidation reactions are crucial for life, they can also be damaging; hence, plants and animals maintain complex systems of multiple types of antioxidants, such as glutathione, vitamin C, and vitamin E as well as enzymes. Low levels of antioxidants, or inhibition of the antioxidant enzymes, causes oxidative stress and may damage or kill cells.
Summary
Atherosclerosis can lead to coronary heart disease. Lipoprotein (a) is an independent risk factor of coronary heart disease. Oxidation of LDL is believed to contribute to the development of atherosclerosis. We can prevent the oxidation of LDL by taking antioxidant.
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