by Temitope Oyedepo

Created on: May 05, 2008

WHAT IS CHOLESTEROL?

Cholesterol is a lipid i.e. a fatty substance which is part of the cell membrane in the body of animals. It is also found in blood circulation of man. The cholesterol found in the blood circulation of man originates from either dietary intake or liver productions. The body needs cholesterol for digestion of dietary fats, making hormones and building cell walls. The blood carries cholesterol in particles called lipoprotein which delivers cholesterol to various body tissues to be used, stored or excreted

Dietary cholesterol comes mainly from animal fats in food such as meat, egg yolk, dairy products, poultry and liver. Food of plant origin does not contain cholesterol at all. After a meal that is high in cholesterol, the cholesterol is absorbed from the intestines into blood circulation. The liver can remove cholesterol from blood circulation and at the same time it can release cholesterol into blood circulation. However, too much of cholesterol circulating in the blood can injure arteries especially the coronary artery that supply the heart. This can lead to a condition called arteriosclerosis which impedes blood flow to the heart. This is what is responsible for many of the heart attacks that occur in man.

The cholesterol that is secreted by the liver is called the Low Density Cholesterol (LDL) cholesterol and it is the form in which cholesterol is carried into the blood. It is bad cholesterol because its elevation in the blood can lead to coronary heart disease. This is because LDL lipoproteins deposit cholesterol on the artery walls. The High Density Cholesterol (HDL) cholesterol is the good cholesterol because they remove cholesterol from the arteries and dispose them through the liver thereby preventing arteriosclerosis. The total cholesterol is therefore the sum of HDL, LDL and VLDL (Very Low Density Level) cholesterol present in the blood.

Heredity and diets play a significant role in the level of LDL cholesterol in the blood. The liver has a number of receptor cells for removing LDL cholesterol in the blood. High blood cholesterol often runs in families. Individuals with family history of few or no receptor cells shall normally experience high level of LDL cholesterol in the blood. Similarly diets that is high in saturated fats and cholesterol raises LDL cholesterol in the blood. Lowering the LDL cholesterol is now the primary focus of preventing arteriosclerosis and heart attack.

Cholesterol levels are determined chemically in the laboratory through the analysis of blood samples taken through a prick in the finger or a vein in the arm. Home cholesterol kits are also available for determining total cholesterol. Cholesterol level is measured in mg/dL. The World Health Organization put the desired level of total blood cholesterol to be lower than 200 mg/dL with LDL lower than 130mg/dL.

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