Cholesterol -- a form of fat found in foods and produced by the liver -- plays a vital role in the body, including hormone production, cellular formation and maintenance, as well as digestion. However, excessive cholesterol -- considered by the American Heart Association as one of six major, controllable risk factors for heart disease -- has been indirectly linked to various types of cardiovascular disease, such as hypertension and coronary artery disease.
Circulation Basics
The circulatory system consists of a closed, looped, network of vessels that carry oxygen and nutrient-rich blood to tissues of the body. To push the blood through the vessels, the heart must contract or pump, which generates a driving pressure for the system. Anything that disrupts the system, such as changes in blood pressure, blockages or weakness of the heart, will ultimately affect the capacity to deliver oxygen and nutrients to vital organs. Excessive cholesterol can have a direct effect on the effectiveness of the circulatory system.
Atherosclerosis
The interior layer of arteries may get damaged from exposure to various substances such as smoking tobacco, genetic alterations, diabetes or infectious organisms. In an attempt by the body to repair itself, the cells that line the arterial walls may absorb free-floating cholesterol into the damaged area. Over the course of years, cholesterol collects in the damaged area, hardens and forms a plaque which partially blocks blood flow. This process of the hardening of arteries -- known as atherosclerosis -- is accelerated with excessive cholesterol in the blood.
High Blood Pressure
Cholesterol can also play an indirect role in elevated blood pressure -- called hypertension. Hypertension occurs as a result of increased resistance to blood flow from atherosclerosis or other factors. As resistance increases, damage to the arterial walls can occur and the heart must beat harder to push blood to vital areas. This places considerable strain on the heart causing it to weaken over time. A.S Contractor, Director of Cardiac Rehabilitation at Cumballa Hill Hospital and Heart Institute reports that untreated hypertension can lead to congestive heart failure -- a condition in which the heart is too weak to adequately circulate the blood.
Plaques
Not only do plaques complicate circulation by narrowing the space in which blood can pass through arteries, but this plaque also carries the risk of breaking and floating downstream to smaller arteries where it can completely block blood flow. If blood flow becomes completely blocked in arteries of the heart, or brain, the result can be a heart attack or stroke.
Coronary Artery Disease
Coronary artery disease describes a condition in which atherosclerotic plaques have formed in the coronary arteries -- the arteries that supply the heart with blood. In a study co-authored by T.G. Allison which examined the relationship of diet and exercise and CAD, Allison reports high cholesterol to be directly related to CAD incidence.
References
- American Heart Association: Why Cholesterol Matters
- "Hyperlipidemia and Dyslipidemia"; Paul M. Gordon; 2003
- "Hypertension"; A.S. Contractor, Neil F. Gordon; 2003
- MayoClinic.com: Arteriosclerosis/Atherosclerosis
- "Mayo Clinic Proceedings"; Achieving National Cholesterol Education Program Goals for Low-density Lipoprotein Cholesterol in Cardiac Patients: Importance of Diet, Exercise, Weight Control, and Drug Therapy; T.G. Allison, R.W. Squires, B.D. Johnson, G.T. Gau; 1999
