Cholesterol is a waxy kind of substance naturally produced by the body and essential for normal body function. Cholesterol is known as a lipid, and forms part of the outer membrane of every body cell, helps to insulate nerve fibers, and to make hormones, the chemical “messengers” of the body.
Contrary to widespread belief, only about 20% of the body’s cholesterol is taken in with food. The remainder is made in the liver. After a meal, dietary cholesterol is absorbed from the intestine and stored in the liver. The liver regulates cholesterol levels in the blood, and can release cholesterol when necessary. Although a certain amount of cholesterol is necessary for our bodies to work properly, too much can cause health problems and be a bad thing.
Confusion arises because cholesterol exists in more than one form in the bloodstream. Since cholesterol is a lipid and does not dissolve in the blood, it is transported around attached to protein of one type or another.
One of the types of cholesterol in the blood is called LDL or low-density lipoprotein (also known as “bad” cholesterol”), and elevated levels are associated with an increased risk of coronary artery disease. LDL lipoprotein deposits cholesterol in the artery walls, causing thickening and hardening of the arteries, together with build up of plaques which gradually narrow the artery, impeding blood flow
The other main form of cholesterol in the bloodstream is HDL or high-density lipoprotein (also known as “good” cholesterol) which helps to prevent arterial plaque build-up by taking cholesterol out of cells, including artery wall cells, and transporting it back to the liver where it can be re-cycled or disposed of.
The third major lipid component of the bloodstream is the collection of triglycerides, fatty acids which also cannot dissolve in the blood. Triglycerides may be combined by the liver with protein to form VDL or very low-density lipoproteins.
How cholesterol affects arteries
When your doctor talks about your cholesterol level he is usually referring to the total concentration of both LDL and HDL cholesterol which gives a general estimate of the risk of developing artery and heart disease – the higher the number, the greater the risk. Blood cholesterol is measured in units called millimoles per litre of blood, often shortened to mmol/L. In the UK it is estimated that 60% of the population have a cholesterol level of 5mmol/L or above, and the suggested or recommended level is 4 or lower.
There is some controversy over what the ideal cholesterol level should be but it is generally reckoned that the lower the better. The situation is slightly more complicated though, by the fact that it is not just the total amount of cholesterol that is important, but more the relative amounts of LDL and HDL. Too much LDL has a definite adverse effect on your risk for disease, as does too little HDL. Thus the Joint British Societies (a group of UK expert societies) recommend a total cholesterol level of less than 4 mmol/L, together with an LDL cholesterol level of less than 2 mmol/L.
Another way of assessing the risk factor which is considered more accurate by some, is to work out the total cholesterol to HDL cholesterol ratio (total chol/HDL). This is calculated by dividing the total cholesterol by the HDL cholesterol to give a number. A higher ratio indicates a higher risk of heart attack, whereas a lower number indicates a lower risk. High total cholesterol and low HDL increases the ratio and is undesirable, while high HDL levels and low total cholesterol lowers the ratio and is more desirable.
It is worth noting that the UK has highest average figures for cholesterol levels in the world, and there is a strong suggestion that lifestyle factors like high saturated fat in the diet, and lack of exercise, are contributory factors. Whilst cholesterol figures are important, and give an indication of risk, a doctor will also take other factors into account in any given case. Factors to consider include age, gender, any family history of heart disease, smoking, high blood pressure, and diabetes.
Cholesterol is a waxy kind of substance naturally produced by the body and essential for normal body function. Cholesterol is known as a lipid, and forms part of the outer membrane of every body cell, helps to insulate nerve fibres, and to make hormones, the chemical “messengers” of the body
Contrary to widespread belief, only about 20% of the body’s cholesterol is taken in with food. The remainder is made in the liver. After a meal, dietary cholesterol is absorbed from the intestine and stored in the liver. The liver regulates cholesterol levels in the blood, and can release cholesterol when necessary. Although a certain amount of cholesterol is necessary for our bodies to work properly, too much can cause health problems and be a bad thing.
Confusion arises because cholesterol exists in more than one form in the bloodstream. Since cholesterol is a lipid and does not dissolve in the blood, it is transported around attached to protein of one type or another.
One of the types of cholesterol in the blood is called LDL or low-density lipoprotein (also known as “bad” cholesterol”), and elevated levels are associated with an increased risk of coronary artery disease. LDL lipoprotein deposits cholesterol in the artery walls, causing thickening and hardening of the arteries, together with build up of plaques which gradually narrow the artery, impeding blood flow
The other main form of cholesterol in the bloodstream is HDL or high-density lipoprotein (also known as “good” cholesterol) which helps to prevent arterial plaque build-up by taking cholesterol out of cells, including artery wall cells, and transporting it back to the liver where it can be re-cycled or disposed of.
The third major lipid component of the bloodstream is the collection of triglycerides, fatty acids which also cannot dissolve in the blood. Triglycerides may be combined by the liver with protein to form VDL or very low-density lipoproteins.
When your doctor talks about your cholesterol level he is usually referring to the total concentration of both LDL and HDL cholesterol which gives a general estimate of the risk of developing artery and heart disease – the higher the number, the greater the risk. Blood cholesterol is measured in units called millimoles per litre of blood, often shortened to mmol/L. In the UK it is estimated that 60% of the population have a cholesterol level of 5mmol/L or above, and the suggested or recommended level is 4 or lower.
There is some controversy over what the ideal cholesterol level should be but it is generally reckoned that the lower the better. The situation is slightly more complicated though, by the fact that it is not just the total amount of cholesterol that is important, but more the relative amounts of LDL and HDL. Too much LDL has a definite adverse effect on your risk for disease, as does too little HDL. Thus the Joint British Societies (a group of UK expert societies) recommend a total cholesterol level of less than 4 mmol/L, together with an LDL cholesterol level of less than 2 mmol/L.
.Another way of assessing the risk factor which is considered more accurate by some, is to work out the total cholesterol to HDL cholesterol ratio (total chol/HDL). This is calculated by dividing the total cholesterol by the HDL cholesterol to give a number. A higher ratio indicates a higher risk of heart attack, whereas a lower number indicates a lower risk. High total cholesterol and low HDL increases the ratio and is undesirable, while high HDL levels and low total cholesterol lowers the ratio and is more desirable.
It is worth noting that the UK has highest average figures for cholesterol levels in the world, and there is a strong suggestion that lifestyle factors like high saturated fat in the diet, and lack of exercise, are contributory factors. Whilst cholesterol figures are important, and give an indication of risk, a doctor will also take other factors into account in any given case. Factors to consider include age, gender, any family history of heart disease, smoking, high blood pressure, and diabetes.
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