Cholesterol is carried in the blood by molecules called
lipoproteins. A lipoprotein is any complex or compound containing both lipid
(fat) and protein. The three main types are:
1. LDL (low density lipoprotein)
People often refer to it as bad cholesterol. LDL carries
cholesterol from the liver to cells. If too much is carried, too much for the
cells to use, there can be a harmful buildup of LDL. This lipoprotein can
increase the risk of arterial disease if levels rise too high. Most human blood
contains approximately 70% LDL - this may vary, depending on the person.
2. HDL (high density lipoprotein)
People often refer to it as good cholesterol. Experts say
HDL prevents arterial disease. HDL does the opposite of LDL - HDL takes the
cholesterol away from the cells and back to the liver. In the liver it is
either broken down or expelled from the body as waste.
3. Triglycerides
These are the chemical forms in which most fat exists in the
body, as well as in food. They are present in blood plasma. Triglycerides, in
association with cholesterol, form the plasma lipids (blood fat). Triglycerides
in plasma originate either from fats in our food, or are made in the body from
other energy sources, such as carbohydrates. Calories we consume but are not
used immediately by our tissues are converted into triglycerides and stored in
fat cells. When your body needs energy and there is no food as an energy
source, triglycerides will be released from fat cells and used as energy -
hormones control this process.