Cholesterol is good and bad for the body. It is a chemical with a ringed structure and a section that dissolves in fats and another that dissolves in water. It is important to consult with a physician regarding the diagnosis and treatment of diseases associated with high cholesterol, as well as for dietary suggestions.
Types of Cholesterol
Cholesterol is a molecule, so to be specific there is only one type of cholesterol, not a good or a bad cholesterol. However, differentiating between good and bad cholesterol does have a use. Cholesterol is derived from the diet and from liver synthesis. When a blood test called a lipid profile is drawn for study, the main components of blood studied include triglycerides, or fats, high density lipoprotein, or HDL, low density lipoprotein, or LDL, and total lipoprotein. Lipoproteins are molecules that float in the blood and contain a combination of fat, cholesterol and proteins. There are a few different types: the LDL is commonly labeled "bad" cholesterol and the HDL is commonly called "good" cholesterol.
Normal Cholesterol Functions
The molecule cholesterol has important function in the body. The cell membrane is like the skin of the cell; it surrounds and protects it. Cholesterol makes the membrane more flexible and able to withstand a greater range of temperature changes without damage. It also is used to synthesize steroid hormones such as the stress hormone cortisol, the mineral and blood pressure regulating hormone aldosterone, and the sex steroids testosterone and estrogen.
Cholesterol Metabolism
The body is able to synthesize enough cholesterol through the liver for its own needs. More than a little dietary cholesterol adds unnecessary cholesterol to the body. The lipoproteins that carry cholesterol are classified according to density. LDL has the highest concentration of cholesterol. It takes the cholesterol out to the cells to be used by them for normal functions. When excess cholesterol is in the blood, it is deposited in the blood vessels walls. In contrast, HDL has a lower concentration of cholesterol. In addition, instead of moving cholesterol out into the body like LDL, HDL moves cholesterol from the tissues to the liver for excretion.
Effects on Health
High LDL levels deposit cholesterol into the blood vessel walls. These become plaques that can narrow and harden the blood vessel walls, leading to organ damage. High LDL is associated with diseases such as heart attacks and strokes. Low levels of HDL are also associated with increased risk of these diseases. High levels of HDL confer a lower risk of developing these diseases.
References
- "Harrison's Principles of Internal Medicine"; Anthony S Fauci et al.; 17th Ed 2008
- "Robbins and Cotran Pathologic Basis of Disease"; Vinay Kumar et al.; 8th Ed 2009
- "Physiology"; Linda S.Costanzo; 4th Ed 2008
- "Lehninger Principles of Biochemistry"; David L. Nelson and Michael M. Cox; 4th Ed 2004
