Good and Bad Cholesterol
~ March 1999 No.70 ~
We hear often hear that too much cholesterol leads to heart disease. So all cholesterol is bad. Right? Well it’s not quite that easy.
Cholesterol is a complex molecule produced by animals as part of normal metabolism. Cholesterol is a building block in many important cell components especially the cell membrane and is the starting point for several hormones. The body can't do without cholesterol. Cholesterol is so important that the body produces its own cholesterol. If there is not enough cholesterol in the diet, then it is produced in the body. A balance between cholesterol from the diet and cholesterol produced by the body is always maintained. An adult on a cholesterol free diet can be producing up to a gram of cholesterol a day. This cholesterol is sent out to the various parts of the body in the blood where it is used. That is why a blood sample is used to measure your cholesterol status.
Early blood cholesterol tests reported total cholesterol values, mainly because they are the easiest and cheapest to measure. For some time it was generally thought that any high blood total cholesterol value was bad. But, as researchers began to understand more about how the body transports and uses cholesterol, it became clear that total cholesterol values were not telling the whole story.
Cholesterol and cholesterol containing molecules are carried through the blood in particles called lipoproteins. The lipoproteins are made up of protein and fat ( generally called lipids) and depending on their use in the body they are different densities. It is this difference in weight that allows medical researchers to separate the many blood lipoprotein fractions. The dense lipoproteins are called high density lipoproteins or HDL's ; low density lipoproteins or LDL's are less dense. As we have learned more about the uses of cholesterol in the body, it has become clear that cholesterol in the LDL's is more important in the formation of atheroscerotic plaques that can build up and restrict or even stop blood flow in the veins and arteries. This is "bad" cholesterol. You want to keep your low cholesterol low. Cholesterol in the HDL of the blood is being used for many of the important functions in the body and is less involved with plaque formation. Cholesterol in the HDL's is "good" cholesterol. You want to keep your HDL high.
The factors that effect the levels of HDL and LDL cholesterol in the blood are complex. It is now clear that any food that lowers LDL cholesterol or raises HDL cholesterol is what we should be looking for.
|chemical formula and name:||C26H44O; (3.beta.)-Cholest-5-en-3-ol; cholesterin.|
|description:||an unsaturated alcohol, a waxy solid at room temperature|
|foods with no cholesterol:||any foods of plant origin, e.g. fruits, vegetables, grains|
|foods that contain cholestero:||animal body tissues, particularly the brain, spinal cord; animal fats or oils. Foods of animal origin, e.g. meats, dairy products, lard, shortening|