Facts and figures

There is a lot of talk these days about lipids and cholesterol and now I've seen something about triglycerides! I am rather muddled about it all. Can you tell me what all these words mean?

Cholesterol is a fatty or oily substance and is one of a group of fatty substances we call lipids. Lipids are essential for the normal functioning of the body's cells. Problems develop when there is too much lipid in the blood. It then settles in the walls of the arteries. The arteries then develop the narrowings which cause heart attacks and angina by restricting the flow of blood to the heart (see the Introduction to this chapter). Doctors often ask for a 'lipid profile': this is a check on the levels of cholesterol and triglycerides in your blood. (Triglyceride is another fatty substance - see below).

Cholesterol plays an essential role in helping our glands make hormones, but its biggest role is in the formation of cell walls. We are able to make all the cholesterol we need in the liver, where it is made from fat. Our problems begin if we have a higher blood cholesterol than we need; this is usually due to eating too much fat (see the question later on hypercholesterolemia).

Triglycerides (pronounced 'try-gli-sir-ides') are the major form of

saturated fats (see later question) which come from food and they are also made in the body to provide energy. If you have a high level of triglycerides and a low level of high density lipoproteins (see next question), you have a greater chance of developing coronary disease. Triglycerides are commonly raised in people who are very overweight, people with diabetes and those who have a high alcohol intake.

I was told that all cholesterol is bad for you. Now I read that there is a 'good' cholesterol and 'bad' cholesterol. What's the difference?

Cholesterol and other fats do not dissolve in the blood. They hitch a ride on proteins which are the taxis transporting the fats around. The combination of fat and protein is a lipoprotein (pronounced 'lie-po-pro-teen'). The 'bad' cholesterol is the low density lipoprotein (LDL): this is the main carrier of harmful cholesterol to your arteries where it builds up to cause narrowings. The high density lipoproteins (HDL) are the good guys: HDL tends to pick up excess cholesterol taking it away from the arteries and transporting it back to the liver for removal. So, for maximum protection, you need:

• your LDL low (L for lousy);

• your HDL high (H for happy).

I'm going to have a complete check-up next month. When I have my cholesterol profile checked, what levels should all these different fats be?

Our total cholesterol should not be above 5.0mmol/litre. The HDL (see question above) should be greater than 1.0 mmol/L in a man, and 1.3 mmol/L in a woman.

The LDL should be 3.0 mmol/L or less - the ideal is 2.6 or less.

Your triglycerides should be less than 1.7 mmol/L, ideally 1.6 or less.

As a rule of thumb, a total cholesterol of 5.0 equals an LDL of 3.0.

However, for coronary patients and those with chronic renal disease or diabetes, the targets are lower:

• cholesterol 4 mmol/L or less;

• LDL 2.0 mmol/L or less.

So remember 5 and 3, and 4 and 2.

Research has shown that lowering cholesterol to these levels in normal people, as well as in coronary patients, helps prevent heart disease in the future. The benefits apply to both men and women.

When I had a lipid profile done on my blood, the doctor told me I had hypercholesterolemia. What does this mean?

Hypercholesterolemia (pronounced 'hi-per-kol-esterol-eemia') means that the total cholesterol is high in the blood. Usually the LDL (see question above) is raised; in women the HDL is higher before the menopause - an effect of their hormones. It is always better to know both profiles (HDL and LDL), as well as the total level, because you don't want to lower a high HDL by mistake. For example, a woman before the menopause may have a high total cholesterol (e.g. 5.8) which is made up mainly of the good HDL (e.g. 2.0).

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