Lowering Your Cholesterol
Medical Author: Benjamin Wedro, MD, FACEP, FAAEM,
Daniel Kulick, MD
Medical Editor: William C. Shiel Jr., MD, FACP, FACR
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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 chemical compound that is naturally produced by the body and is a combination of lipid (fat) and steroid. Cholesterol is a building block for cell membranes and for hormones like estrogen and testosterone. About 80% of the body's cholesterol is produced by the liver, while the rest comes from our diet. . 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, dietary cholesterol is absorbed from the intestine and stored in the liver. The liver is able to regulate cholesterol levels in the blood stream and can secrete cholesterol if it is needed by the body.
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 manufactures and secretes LDL cholesterol into the blood. It also removes LDL cholesterol from the blood by active LDL receptors on the surface of its cells. A decrease number of liver cell 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 (hyper= more + cholesterol + emia= in blood) 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.
Next: Does lowering LDL cholesterol prevent heart attacks and strokes? »
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