Definition

Cholesterol is a fatty substance found in animal tissue and is an important component to the human body. It is manufactured in the liver and carried throughout the body in the bloodstream. Problems can occur when too much cholesterol forms an accumulation of plaque on blood vessel walls, which impedes blood flow to the heart and other organs. The highest cholesterol content is found in meat, poultry, shellfish, and dairy products.

Description

Cholesterol is the Dr. Jekyll and Mr. Hyde of medicine, since it has both a good side and bad side. It is necessary to digest fats from food, make hormones, build cell walls, and participate in other processes for maintaining a healthy body. When people talk about cholesterol as a medical problem, they are usually referring to high cholesterol. This can be somewhat misleading, since there are four components to cholesterol. These are:

• LDL, the so-called bad cholesterol
• HDL, the so-called good cholesterol
• triglycerides, a blood fat lipid that increases the risk for heart disease
• total cholesterol

The U.S. Food and Drug Administration (FDA) estimates that 90 million American adults, roughly one-half of the adult population, have elevated cholesterol levels. High LDL (low-density lipoprotein) is a major contributing factor of heart disease. The cholesterol forms plaque in the heart's blood vessels, which restricts or blocks the supply of blood to the heart, and causes a condition called atherosclerosis. This can lead to a heart attack, resulting in damage to the heart and possibly death.

In 2001, chemical researchers found a link between cholesterol and Alzheimer's disease. Reducing the amount of cholesterol in the cells appears to block attachment of senile plaques to the brain's neurons. (The plaques begin the process that eventually kills brain neurons.) More study remains to test the effects of cholesterol on Alzheimer's.

The population as a whole is at some risk of developing high LDL cholesterol in their lifetimes. Specific risk factors include a family history of high cholesterol, obesity, heart attack or stroke, alcoholism, and lack of regular exercise. The chances of developing high cholesterol increase after the age of 45. One of the primary causes of high LDL cholesterol is too much fat or sugar in the diet, a problem especially true in the United States. Cholesterol also is produced naturally in the liver and overproduction may occur even in people who limit their intake of high cholesterol food. Low HDL and high triglyceride levels also are risk factors for atherosclerosis.