Cholesterol is a type of lipidFat or oils, composed of fatty acids and glycerol. found in the cell membrane, and it is also used to synthesise sex hormones.
It is important for our health to keep cholesterol in the bloodstream at appropriate levels. Too much cholesterol in the blood can cause health conditions like CVD. Increased levels can be as a result of a diet high in saturated fatFat that contains only saturated fatty acids. Foods which contain saturated fat include butter, cream and cheese. or cholesterol.
Cholesterol is produced by all cells but 25% of all cholesterol produced comes from the liver.
There are two types of cholesterol carrying proteins:
HDL
LDL
HDLs are high-density lipoproteins. The role of HDL is to transport excess cholesterol from the rest of the body to the liver for elimination from the body.
LDLs are low-density lipoproteins. Their role is to transport cholesterol from the liver to the rest of the body and deposit cholesterol inside the arteries.
Cholesterol levels are also controlled by a negative feedback system:
cells have LDL receptors on their surface which allow cholesterol to be deposited inside the cells by LDLs
once there is an adequate amount of cholesterol inside the cell, synthesis of new LDL receptors are inhibited which reduces the amount of cholesterol that is absorbed into the cells
as a result, excess LDL carried cholesterol is deposited inside the arteries, lining the endothelium causes an atheroma to be formed