Cholesterol is a waxy substance that is manufactured in your liver and small intestine and found virtually everywhere in your body. Its chemical structure is similar to that of steroids, and is seen as a building block of testosterone and serves as a chemical ancestor of other hormones that, for better or worse, have major effects on your muscles such as progesterone, oestrogen and cortisol.
Cholesterol is carried around the bloodstream by molecules called lipoproteins. There are 2 types, low-density lipoproteins (LDL), which carry cholesterol to various tissues, and high-density lipoproteins (HDL), which carry cholesterol back to the liver so it can be removed from the body.
What causes high cholesterol?
There are several factors that may contribute to high blood cholesterol:
- a diet that’s high in saturated fat and, less so, high in cholesterol
- lack of exercise may increase LDL (“bad”) cholesterol and decrease HDL (“good”) cholesterol
- family history – people are at a higher risk of high cholesterol if they have a direct male relative aged under 55 or female relative aged under 65 affected by coronary heart disease
- being overweight, which may increase LDL (“bad”) cholesterol and decrease HDL (“good”) cholesterol
- age and sex – cholesterol generally rises slightly with increasing age, and men are more likely to be affected than women
- drinking alcohol excessively.
Rarely, high cholesterol can be caused by a condition that runs in the family called a lipid disorder (familial hypercholesterolemia). Other health conditions such as poorly controlled diabetes, certain kidney and liver diseases and an under active thyroid gland may also cause cholesterol levels to rise. Some medicines such as beta-blockers, steroids or thiazides (a type of diuretic) may also affect blood lipid levels.
LDL is found in larger quantities in the bloodstream. It causes problems because as it travels around the body to your organs, its lower density allows some of the cholesterol to stick to the blood vessel walls, and eventually block them. As the vessels become increasingly blocked the blood flow to your hearts stops, and eventually the heart itself stops. Experts on all sides of the nutrition debate seem to agree that this is not a good thing. LDL is sometimes referred to as “bad cholesterol”.
HDL works in the exact opposite to LDL. Because of its high density, HDL transports cholesterol without letting any of it stick to artery walls along the way. HDL saves your heart by pulling excess cholesterol out of places where it can work its mischief and returns it to the liver. HDL is sometimes referred to as “good cholesterol”. Women tend to have a higher HDL cholesterol level than men.
This is another type of blood fat worth mentioning. This is the storage form of fat and elevated levels in the blood are associated with increased risk of heart disease and clogging of the arteries.
How diet can affect blood cholesterol.
Only about 20% of cholesterol comes directly from diet – the other 80% is produced by the liver. However, a diet high in saturated fats and cholesterol can cause the liver to produce more LDL (“bad”) cholesterol. The amount that diet influences cholesterol levels varies from person to person and is probably an inherited characteristic. Some people who eat high-fat diets have high cholesterol levels; others may have normal or low cholesterol levels.
How can you measure your Cholesterol?
Simple… all you have to do is go to your local GP, during a hospital appointment or a part of a health examination. It involves a blood test, and requires you to give a blood sample either by using a needle and syringe, or by using a finger prick.
Cholesterol is measured in units called mill moles per litre of blood; normally know as ‘mmol/litre’. It is seen healthy to have a total cholesterol level under 5 mmol/litre and an LDL level under 3 mmol/litre.
Doctors will look at the ratio between total cholesterol and HDL when estimating the risk of a person getting coronary heart disease (CHD). A lower rate is preferred, as this indicates that the level of HDL is high.
The main aim of lowering cholesterol is to reduce the risk of heart disease. The type of treatment depends on the overall risk of heart disease. There are two ways to treat high cholesterol. The first is with simple lifestyle changes including changing diet, managing weight, increasing exercise, and quitting smoking. The second is to combine lifestyle changes with cholesterol-lowering medicines.
Healthy eating can reduce cholesterol. Diet should be low in saturated fats in particular, and low in fat overall. Biscuits, cakes, pastries, red meat, hard cheese, butter and foods containing coconut or palm oil all tend to be high in saturated fats. Large amounts of cholesterol are found in a few foods, including eggs and offal such as liver and kidneys. Although dietary cholesterol does not usually contribute much to blood cholesterol, it is still advisable to limit these foods to three servings a week if you have high cholesterol.
It is also important to eat plenty of fibre, especially soluble fibre, which is thought to lower cholesterol. It is found in fruits and vegetables, beans and oats. Aim to eat at least five portions of fruit and vegetables each day.
Cholesterol lowering medicines are considered for people who already have CHD, or are at high risk of getting it because they have other risk factors.
The main group of medicines for lowering cholesterol are statins. Examples include simvastatin (Zocor) and atorvastatin (Lipitor). They work by reducing the production of cholesterol in the liver. Occasionally these drugs have side effects such as indigestion and muscle pains. Other types of drugs to reduce cholesterol are called fibrates and nicotinic acids, but these are generally less effective or have more side effects.
Reducing the risk of heart disease
A healthy lifestyle, exercising on most days, eating a low fat diet, not smoking and drinking alcohol within the recommended limits will help reduce the risk of coronary heart disease.