Cholesterol is a four-ringed molecule. It is classified as a lipid, which means it is fat-soluble like oils, fats and the vitamins A, D, E and K. This is opposed to water-soluble molecules. Cholesterol is synthesized by the body and required for normal functioning, but too much cholesterol is unhealthy. It is important to consult with a physician for dietary advice and the diagnosis and management of health conditions.
Lipoproteins
Sometimes cholesterol is classified as simply "good cholesterol" and "bad cholesterol." Good and bad cholesterol do not actually refer to different chemical properties of the cholesterol molecule itself. Cholesterol does not float freely through the blood. It is packaged with other lipids such as fat and fatty acids and proteins. The combination of lipid and protein is called a lipoprotein. These are classified by density: very low density lipoprotein, low density lipoprotein, intermediate density lipoprotein, high density lipoprotein, and chylomicrons. Low density lipoprotein -- LDL -- is the "bad cholesterol" and high density lipoprotein -- HDL -- is the "good cholesterol."
Beneficial Functions
The cholesterol molecule is used to synthesize steroid hormones. The adrenal gland synthesizes many of these hormones, such as cortisol, aldosterone, testosterone and estrogen. Cortisol helps the body respond to stress. Aldosterone balances the blood pressure, fluids and electrolytes. Testosterone and estrogen are the male and female sex steroids. In addition, cholesterol helps keep all cells flexible and resistant to temperature fluctuations.
Detrimental Effects
High levels of total lipoproteins and low density lipoprotein are associated with adverse health. The cholesterol deposits in the walls of the arteries, creating plaques that narrow the arteries and ultimately restrict blood flow to the organs. The plaque buildup is known as atherosclerosis, and its presence increases the risk of heart disease and strokes.
Interventions
The liver synthesizes enough cholesterol for the body, and dietary cholesterol contribute to high blood cholesterol. A proper diet, exercise, and active lifestyle are primary treatments for high cholesterol. If these interventions fail to work, medical therapy may be necessary. Certain drugs such as statins interfere with the synthesis of LDL cholesterol, and other drugs work by other mechanisms. If atherosclerosis advances, sometimes the plague can be removed by procedural interventions, but it is best to prevent their formation in the first place.
References
- "Harrison's Principles of Internal Medicine"; Anthony S Fauci, et al.; 17th Ed 2008
- "Lehninger Principles of Biochemistry"; David L. Nelson, et al.; 4th Ed 2004
