Cholesterol is a molecule that is necessary and important in most humans, animals, plants and fungi

Classified and termed as a “sterol” which is a combination of a steroid and alcohol.

Is essential for life but in excess can lead to serious complications

Cholesterol in a human is produced in the liver

Can also be added to the blood by ingestion from the diet, then it can be recycled and reabsorbed by the digestive system.

Is slightly water soluble

Elevated cholesterol leads to Hypercholesterolemia


–  Production of cell membranes
–  Maintenance of cell membranes
–  Helps transport within cells
–  Important player in “endocytosis” of the cell – allows for absorption by cells
–  Can be converted into bile
–  Can be converted into other products


Food products:

–  Animal fat – along with triglycerides and phospholipids
–  Cheese
–  Shrimp
–  Pork
–  Beef
–  Poultry
–  Shrimp
–  Egg yokes

Liver Synthesis

–  The bulk of cholesterol is produced here
–  Occurs during a reaction of other molecules
–  Other sites include:
1.)  Intestines
2.) Adrenal gland
3.) Reproductive organs


–  Is transported in blood by lipoproteins
–  Lipoproteins are complex circular structures
–  Triglycerides are also transported witin these structures

Types of Lipoproteins

1.)  VLDL –  Very low density lipoproteins
2.)  IDL –  Intermediate density lipoproteins
3.)  LDL –  Low density lipoproteins
4.)  HDL –  High density lipoproteins
5.)  Chylomicrons



As previously mentioned cholesterol is excreted from liver into bile

A large portion of bile is reabsorbed and the remaining is lost in feces