While cholesterol is often vilified in the media for its role in cardiovascular disease, it's actually an important biomolecule that the human body's cells need in order to maintain health and wellness. Excess cholesterol in the diet and in the body, however, can be quite harmful, and having too much cholesterol is linked with increased incidence of arterial and heart disease.
Cholesterol's Role in Good Health
There are several important purposes of cholesterol in the body. First, the molecule is a lipid, meaning that it dissolves in fat. As such, explain Drs. Reginald Garrett and Charles Grisham in their book "Biochemistry," cholesterol can dissolve in the fatty membranes surrounding cells. There, the cholesterol helps to maintain appropriate rigidity of cell membranes. Additionally, the body uses cholesterol to make vitamin D. In the presence of sunlight, cells convert cholesterol in the skin to vitamin D.
Sources of Cholesterol
Body cells need cholesterol so much that they can obtain it in two ways--they can get it from the bloodstream, where it ends up after having been consumed, or they can make it from other molecules. Since cells can make their own cholesterol as necessary, high quantities of cholesterol in the diet almost always lead to excess cholesterol in the blood, and cells won't take up cholesterol in excess of their needs, meaning that excess cholesterol remains in the bloodstream.
"Bad" vs. "Good" Cholesterol
Blood cholesterol falls into one of two categories, depending upon the direction in which the cholesterol is moving, explain Drs. Mary Campbell and Shawn Farrell in their book "Biochemistry." Cholesterol headed toward the body cells is packaged into LDL transporters, and is sometimes called "bad" cholesterol. Cholesterol headed toward the liver for disposal is packaged into HDL transporters, and is sometimes called "good" cholesterol. High LDL levels are associated with disease processes, while high HDL levels are not.
It's important to note that while many people think that there are two kinds of cholesterol--"good" and "bad"--in fact, there's only one kind, because cholesterol is a specific molecule, and has no subtypes. There are, however, two types of cholesterol transporters. Because LDL transporters carry cholesterol to the body cells, if the cells have plenty of cholesterol and won't take up any more from the blood, LDL-contained cholesterol can build up in the bloodstream, explains Dr. Lauralee Sherwood in her book "Human Physiology." This leads to disease.
When cholesterol builds up in the blood, it can end up forming plaque on arterial walls, notes Dr. Gary Thibodeau in his book "Anatomy and Physiology." This causes narrowing of the arteries, and can restrict blood flow through the vascular system. This is of particular concern when the narrowed arteries carry blood to the brain or to the heart itself. In addition, plaques can lead to hardening of the arteries, or atherosclerosis, which in turn increases risk of heart attack and stroke.
- “Biochemistry”; Reginald Garrett, Ph.D. and Charles Grisham, Ph.D.; 2007
- “Biochemistry”; Mary Campbell, Ph.D. and Shawn Farrell, Ph.D.; 2005
- “Human Physiology”; Lauralee Sherwood, Ph.D.; 2004
- “Anatomy and Physiology”; Gary Thibodeau, Ph.D.; 2007
- meat image by Svetlana Kashkina from Fotolia.com
This article reflects the views of the writer and does not necessarily reflect the views of Jillian Michaels or JillianMichaels.com.