Coronary artery disease, or atherosclerosis, is a progressive disease of the arteries that supply the heart muscle, and is the leading cause of death in the United States. According to the American Heart Association, coronary artery disease caused more than 425,000 deaths in the United States in 2006, and more than 17 million Americans have the disease as of 2010. Cholesterol is a steroid involved in cell structure, absorption and metabolism. High levels of cholesterol are implicated in the development of coronary artery disease.
Types
Cholesterol does not dissolve in the blood, and is therefore transported throughout the bloodstream in carrier structures called lipoproteins. These lipoproteins are classified based on their density, which is related to their cholesterol content. Low-density lipoproteins (LDL), known as "bad cholesterol," contain high levels of cholesterol, while high-density lipoproteins (HDL), known as "good cholesterol," contain low levels of cholesterol. LDL cholesterol is linked to an increased risk of coronary artery disease, while HDL cholesterol is linked to reduced risk.
Effects
The development of coronary artery disease is a process that takes many years to develop. Early on, bad cholesterol becomes embedded within the innermost layer of the blood vessels in the heart, forming what is known as a plaque. The developing plaque then becomes modified in a way that allows inflammatory and other types of cells to enter the plaque. In later stages, the plaque calcifies and becomes brittle. Large plaques can restrict blood flow to the heart or rupture and cause an immediate heart attack.
Benefits
According to the American Heart Association, good cholesterol may function by transporting cholesterol to the liver, where it is eliminated from the body rather than deposited in a plaque. Several studies have shown that people with higher levels of good cholesterol are less likely to develop coronary artery disease.
Sources
The major source of dietary cholesterol is meat that is high in saturated fat, which is sometimes called "bad fat." It is also found in egg yolk, cheese, butter and shellfish.
Expert Insight
The American Heart Association publishes guidelines that establish healthy levels of cholesterol. They recommend keeping total cholesterol below 200mg/dL and LDL cholesterol below 100mg/dL. For HDL cholesterol, they recommend values greater than 40mg/dL for men and 50mg/dL for women. HDL cholesterol levels above 60mg/dL are considered protective.
Considerations
Bad cholesterol can be lowered through lifestyle changes. General dietary recommendations include avoiding high cholesterol foods and consuming fruits, vegetables and fish. For people unable to lower cholesterol through diet alone, medications are available to reduce the levels of bad cholesterol. Good cholesterol can be increased with exercise and consumption of fish oils. There are also medications designed to raise good cholesterol levels.
References
- American Heart Association: Cardiovascular Disease Statistics
- Centers for Disease Control: Heart Disease
- "Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 8th Edition"; Peter Libby, M.D. and Ronald Krauss, M.D.; 2008
