Lowering Your Cholesterol
Heart Attack Prevention Series
Medical Author Revision: Dennis Lee, M.D.,
Daniel Kulick, M.D.
Medical Editor: William C. Shiel Jr., MD, FACP, FACR
Additional Heart Attack Prevention Series Information (related articles)
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Mr. D.T.'s Story - There Is Hope
Medical Author: Dennis Lee, M.D.
 I am sure many of you have been
reminded by doctors, nurses, and public health officials to lose excess weight,
quit smoking cigarettes, exercise regularly, and eat less saturated fat and sweets. Here is a real
life example of how effective these measures can be.
Mr. DT is a healthy and active 50-year-old man. He exercises 6 days a week. He does not smoke cigarettes. He tries to hold down fat and cholesterol intake; he only cheats on weekends and holidays. He is slightly overweight (only 12 pounds heavier than ideal body weight). His mild high blood pressure has been well controlled with an oral medication called
an ACE inhibitor. There is no family
history of any heart disease.
Last week, he asked his doctor for a complete blood panel
that includes cholesterol and triglyceride levels, since
he has not had one for more than a year. The nurse who drew his blood first
noticed there was something wrong; Mr. DT's serum was abnormally discolored.
Before performing blood chemistry measurements, she had to spin the blood sample
in a centrifuge to separate the red and white blood cells from the serum. Normal
serum is clear yellow in color. But Mr. DT's serum was pink and milky. Milky
serum indicates excess chylomicrons (protein complexes that contain high amounts
of triglycerides and cholesterol).
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What is cholesterol?
Cholesterol is a fatty substance (a lipid) that is an
important part of the outer lining (membrane) of cells in the body of animals. Cholesterol is also
found in the blood circulation of humans. The cholesterol in a person's blood
originates from two major sources; dietary intake and liver production. Dietary
cholesterol comes mainly from meat, poultry, fish, and dairy products. Organ
meats, such as liver, are especially high in cholesterol content, while foods of
plant origin contain no cholesterol. After a meal, cholesterol is absorbed by
the intestines into the blood circulation and is then packaged inside a protein
coat. This cholesterol-protein coat complex is called a chylomicron.
The liver is capable of removing cholesterol from the blood circulation as
well as manufacturing cholesterol and secreting cholesterol into the blood
circulation. After a meal, the liver removes chylomicrons from the blood
circulation. In between meals, the liver manufactures and secretes cholesterol
back into the blood circulation.
What are LDL and HDL
cholesterol?
LDL cholesterol is called "bad" cholesterol, because elevated levels of LDL
cholesterol are associated with an increased risk of coronary heart disease. LDL lipoprotein
deposits cholesterol on the artery walls, causing the formation of a hard, thick
substance called cholesterol plaque. Over time, cholesterol plaque causes
thickening of the artery walls and narrowing of the arteries, a process
called atherosclerosis.
HDL cholesterol is called the "good cholesterol" because HDL cholesterol
particles prevent atherosclerosis by extracting cholesterol from the artery
walls and disposing of them through the liver. Thus, high levels of LDL
cholesterol and low levels of HDL cholesterol (high LDL/HDL ratios) are risk
factors for atherosclerosis, while low levels of LDL cholesterol and high level
of HDL cholesterol (low LDL/HDL ratios) are desirable.
Total cholesterol is the sum of LDL (low density) cholesterol, HDL (high
density) cholesterol, VLDL (very low density) cholesterol, and IDL (intermediate
density) cholesterol.
What determines the level of LDL cholesterol in the blood?
The liver not only manufactures and secretes LDL cholesterol into the blood;
it also removes LDL cholesterol from the blood. A high
number of active LDL receptors on the liver surfaces is associated with the
rapid removal of LDL cholesterol from the blood and low blood LDL cholesterol
levels. A deficiency of LDL receptors is associated with high LDL cholesterol
blood levels.
Both heredity and diet have a significant influence on a person's LDL, HDL
and total cholesterol levels. For example, familial hypercholesterolemia (FH)
is a common inherited disorder whose victims have a diminished number or
nonexistent LDL receptors on the surface of liver cells. People with this
disorder also tend to develop atherosclerosis and heart attacks during early adulthood.
Diets that are high in saturated fats and cholesterol
raise the levels of LDL cholesterol in the blood. Fats are classified as
saturated or unsaturated (according to their chemical structure). Saturated fats
are derived primarily from meat and dairy products and can raise blood
cholesterol levels. Some vegetable oils made from coconut, palm, and cocoa are also high in saturated fats.
Does lowering LDL
cholesterol prevent heart attacks and strokes?
Lowering LDL
cholesterol is currently the primary focus in
preventing atherosclerosis and heart attacks. Most doctors now believe that the
benefits of lowering LDL cholesterol include:
- Reducing or stopping the formation of new cholesterol
plaques on the artery walls;
- Reducing existing cholesterol plaques on the artery
walls;
- Widening narrowed arteries;
- Preventing the rupture of cholesterol plaques, which
initiates blood clot formation;
- Decreasing the risk of heart attacks; and
- Decreasing the risk of strokes. The same measures that
retard atherosclerosis in coronary arteries also benefit the carotid and cerebral arteries (arteries that
deliver blood to the brain).
Next: How can LDL cholesterol levels be lowered? »
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From the Doctors at MedicineNet.com  |
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- Statins - Read about statins, cholesterol lowering medications like Levacor, Zocor, Pravachol, Lipitor, Crestor, and more. Side effects, drug interactions, and patient information is also provided. Source:MedicineNet
- lovastatin, Mevacor, Altocor - Specifies the medication lovastatin (Mevacor, Altocor) a cholesterol- lowering drug used to inhibit the production of cholesterol by the liver. Article includes descriptions, uses, drug interactions, and side effects. Source:MedicineNet
- Homocysteine - Read about the test for homocysteine levels in the blood. High levesl of homocysteine include increased risk of heart attacks, strokes, blood clots, and Alzheimer's disease.
Source:MedicineNet
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