cholesterol

• Cholesterol is a type of lipid found in the cell membrane, and it is also used to synthesise sex hormones.
• Too much cholesterol in the blood can cause health conditions like CVD. Increased levels can result from a diet high in saturated fats 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. They transport cholesterol from the liver to the rest of the body and deposit cholesterol inside the arteries.
• A negative feedback system also controls cholesterol levels:

  1. cells have LDL receptors on their surface which allow cholesterol to be deposited inside the cells by LDLs
  2. once there is an adequate amount of cholesterol inside the cell, synthesis of new LDL receptors is inhibited which reduces the amount of cholesterol that is absorbed into the cells
  3. as a result, excess LDL carried cholesterol is deposited inside the arteries, lining the endothelium causing an atheroma to be formed
• A higher ratio of HDL to LDL will result in lower blood cholesterol levels and will reduce the chances of developing atherosclerosis.
• A diet low in saturated fats and regular physical activity can raise HDL levels.
• We can also manage cholesterol levels with medication. Prescribed drugs such as statins can reduce blood cholesterol levels by inhibiting synthesis of cholesterol in the liver.