MedClick

Cholesterol is a fat-like, waxy substance found in our bodies. It comes from two main sources; namely in the foods we eat (e.g. egg yolks, meat, or whole milk dairy products) and our own bodies. That's right; our own bodies produce cholesterol in the liver. The liver is able to produce enough cholesterol for the needs of the body. Cholesterol is a necessary substance, it is found in all of our cell membranes; it insulates nerve tissue, and is vital in the production of steroid hormones such as testosterone and oestrogen; it is also used in the production of bile which aids in the digestion of food. Cholesterol-related problems can arise when the level of cholesterol rises above that which is optimal or when there is an imbalance between "good" and "bad" cholesterol.

High levels of cholesterol in our bodies are often linked to our diet but genetics can also be a factor. There are three main types of cholesterol:

1. Low Density Lipoprotein (LDL) often referred to as bad cholesterol, is believed to be responsible for arterial disease such as atherosclerosis. It carries cholesterol from the liver to the cells. If there is too much of it, the excess builds up in the blood vessels and causes the blockages associated with atherosclerosis.
2.  High Density Lipoproteins (HDL) often called good cholesterol, is thought to protect the arteries from a build up of plaques (as seen in atherosclerosis). It carries cholesterol from the cells to the liver for re-absorption or elimination (as waste products in stools).
3. Triglycerides - these fatty substances come mainly from the foods we eat, specifically dairy products, meat and cooking oils; but they are also produced in small amounts by the liver. They are the main energy source for the cells of our bodies.

It is the proportion of LDL cholesterol to HDL cholesterol that influences the degree to which atherosclerosis is likely to cause cardiovascular risk. The amount of cholesterol in the blood can be measured with a blood test. When interpreting the results your doctor will tell you whether your cholesterol level can endanger your health but we have set out some of the indicators which your doctor will be looking for. The ratio between HDL and LDL and total cholesterol is the key consideration, rather than the total cholesterol measurement itself. Below are the readings considered optimal by the medical profession:

• Total cholesterol - under 5.0mmol/l
• LDL - under 3mmol/l
• HDL - over 4 - but the higher the better
• Cholesterol ratios - these ratios can be calculated by dividing your total cholesterol and LDL numbers by your HDL numbers. If the result is a ratio between 2.6 and 4 for total cholesterol to HDL cholesterol, it is good. A ratio of less than 2.5 for HDL to LDL cholesterol is best (remember this is the one used most to assess risk of heart disease and stroke).

When the amount of these LDL cholesterol molecules circulating in the blood is greater than the amount the cells are able to use, the excess is generally deposited in the walls of the arteries causing a hardening and narrowing of the vessels, (a condition called atherosclerosis). This, in turn, can lead to heart attacks, strokes and other related conditions.

Where does exercise fit in?

This is perhaps one of the simplest explanations out there. Exercise causes your metabolism to increase which in turn, requires more energy from the body and so your cells use up more of the cholesterol in the body to provide more energy.

The production of more energy leads to a lowering of your cholesterol levels especially when combined with a reduction in the amount of fatty acids consumed in your food.

The best form of exercise reported for this is brisk walking followed closely by aerobic exercise. A four mile brisk walk will burn off more fat than a four mile run.

You should aim for a 30-45 minute walk 3-4 times per week for optimum benefit. You can pace it according to your own ability and can incorporate it into your daily life e.g. walking to work or part of the way, or taking a walk during your lunch break. Even walking up and down the stairs instead of taking the lift will make a difference.

All in all, the more we exercise, the more fat we utilise for energy and so the less there is available to clog up our blood vessels.