Cholesterol refers to a class of compounds that are important structural components of cell membranes. Cholesterol also forms steroid-type hormones such as estrogen and testosterone. This substance is so important that your body produces its own supply. In addition to endogenous cholesterol produced by your body, dietary sources contribute to your total cholesterol level. Limiting the amount of animal products in your diet is one way to lower cholesterol.
Definitions
A metabolite is chemical that is produced when a substance is broken down in the body. Drugs and naturally occurring substances in the body break down and produce metabolites. Some drugs, such as chlorpromazine, produce more than 100 metabolites. Cholesterol metabolites are produced through a process called catabolism. Unlike metabolism, the process of creating something the body needs, catabolism is the process of breaking down a substance.
High Cholesterol Levels
The American Heart Association reports that cholesterol levels less than 200 mg/dL lower the risk of heart disease. If such levels cannot be achieved by diet alone, medication may be useful. Different medications have several mechanisms of action. For example, statins block the production of cholesterol in the liver. Other drugs act by preventing the absorption of dietary cholesterol. No drug works by increasing the number or type of cholesterol metabolites.
Cholesterol Catabolism
Researchers have been studying cholesterol catabolism since 1960. Cholesterol doesn't easily degrade, which is why the body doesn't use it as fuel. This difficulty in breaking down cholesterol partially explains why so many people have high cholesterol levels. Cholesterol metabolites are produced through bile acids and enzymes. Bile acids are responsible for 90 percent of cholesterol catabolism. Liver enzymes are responsible for the remainder of cholesterol catabolism.
Cholesterol Metabolites
An enzyme called lecithin cholesterol acyltransferase converts cholesterol and phosphatidylcholine into cholesterol esters. Cholesterol esters are found in the adrenal glands and in the fatty atherosclerotic plaques.
Cholesterol can also oxidize and form oxygenated compounds called oxysterols. This process can happen with or without enzymes. Oxysterols can migrate through membranes more easily than cholesterol. Some oxysterols, such as 7β-hydroxycholesterol, are particularly interesting because they may be involved in Alzheimer's.
References
- "Journal of Biological Chemistry"; Catabolism in Vitro of Cholesterol; M. W. Whitehouse, et al.; January 1961
- The AOCS Lipid Library: Steroids 1. Cholesterol and Cholesterol Esters; William W. Cristie; March 2011
- American Heart Association; About Cholesterol; June 2011
- American Heart Association; What Your Cholesterol Levels Mean; June 2011
