Role of cholesterol in the development of cardiovascular diseases(Part 1)

Nature of cholesterol

Cholesterol is a form of fatty substance needed by your body for the maintenance of cell membranes,and production of bile acid and hormones[1]. With insufficient cholesterol, your cells will be adversely affected because the integrity of the cell membrane which encloses all its structures will be impaired. In addition, the quality of your bile acid which is one of the components of your bile and the different hormones that you need every minute of your life will deteriorate.

Cholesterol can be sourced from: (1) the foods and drinks that you take, and (2)the different chemical reactions taking place in your body. Because it is produced in your body, it has been postulated that probably you do not need the cholesterol coming from your foods and drinks! Hence, the cholesterol being produced in your body is enough to meet your needs[1]! However, it is not possible to totally remove all the cholesterol that is in your foods! It is impossible! Thus, if you want to control your dietary intake of it, you need to be choosy with your foods, selecting only those which are not rich in it (Consult Powertec 144). Examples of foods rich in cholesterol are meats, liver and other organ meats, dairy foods, egg yolks, and shellfish[2].

Transfer and elimination of cholesterol

When cholesterol is absorbed in your gastrointestinal tract, it travels in the bloodstream in the form of lipoproteins. It cannot travel as cholesterol; it has to be in the form of lipoproteins. There are two lipoproteins that carry cholesterol: (1) the low density lipoprotein (LDL) and the (2) high density lipoprotein (HDL). The LDLcarry the majority of cholesterol, around 75 to 85%, while the HDL carry approximately 15 to 25%[1]. Thus, they are called either LDL-cholesterol or HDL-cholesterol.

Aside from having different densities, the LDL-cholesterol and the HDL-cholesterol have different behavior when they are in the bloodstream. The LDL-cholesterol tends to bring the cholesterol away from the liver; that is, it brings its passengers to the far-flung structures of the body, such as in the blood vessels and peripheral tissues. Consequently, the cholesterol molecules are deposited in these organs. Specifically, when the cholesterol molecules are deposited in the inner lining of your medium to large blood vessels, these structures become inelastic, leading to the development of hypertension. When they are deposited in the small blood vessels of your heart, you will have heart disease and possible heart attack[3]. Since the LDL-cholesterol contributes to the development of cardiovascular diseases, such as hypertension and heart diseases, it is also known as the bad cholesterol.

The HDL-cholesterol, on the other hand, carries cholesterol molecules from the peripheral organs, such as the muscles and blood vessels, and brings them back to the liver—otherwise known as the reverse cholesterol transport—where they are taken up and incorporated as part of the bile. In a way, these cholesterol molecules were removed from the bloodstream, without inflicting any damage to the blood vessels and other organs of your body. Since the HDL-cholesterolhelped to remove cholesterol in the blood, it is also referred to as the good cholesterol.

Injury to the inner lining of blood vessels and cholesterol deposition

The innermost layer of your blood vessels is called the endothelium, and lately this structure has been receiving a lot of research attention because it has been becoming more clear that it is very much involved in the causation of atherosclerosis (deposition of fatty substances in the blood vessels) andhypertension. It has been postulated that the deposition of fatty substances is preceded by the injury of the endothelium.

(To be continued)

References:

  1. Sacher, Ronald A. and Richard A. McPherson. Widmann’s Clinical Interpretation of Laboratory Tests. F. A. Davis Company, Philadelphia, 2000.
  2. http://www.nhlbi.nih.gov/news/spotlight/fact-sheet/questions-and-answers-cholesterol-and-health-nhlbi-nutritionist-janet-de-jesus-ms-rd
  3. http://www.nhlbi.nih.gov/health/resources/heart/heart-cholesterol-hbc-what-html
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