What is cholesterol?

Cholesterol is a fatty substance that is an important part of the outer lining of cells in the body of animals. Cholesterol is also found in the blood circulation of humans.

When cholesterol is measured in the blood 3 cholesterol levels are determined: LDL-cholesterol (bad cholesterol), HDL-cholesterol (good cholesterol) and triglycerides. LDL-cholesterol or "bad cholesterol" has the property to build up plaque on the inner walls of the arteries which feed the heart and brain. Together with other substances the LDL-cholesterol forms a plaque that can clog the arteries. HDL-cholesterol or "good cholesterol" carries cholesterol away from the bloodstream and back to the liver thereby decreasing the risk of plaque build-up. Triglycerides are the normal fats. Blood triglyceride may also play a role in forming plaque.

The cholesterol in a person’s blood originates from two major sources, dietary intake and liver production. Dietary cholesterol comes mainly from meat, poultry, fish, and dairy products. After a meal, cholesterol is absorbed by the intestines into the blood circulation and is then packaged inside a protein coat. The liver is capable of removing cholesterol from the blood circulation as well as manufacturing cholesterol and secreting cholesterol into the blood circulation. After a meal, the liver removes cholesterol from the blood circulation. In between meals, the liver manufactures and secretes cholesterol back into the blood circulation.