By Medifit Education.
WHAT IS CHOLESTEROL?
Cholesterol is a fatty substance known as a lipid and is vital for the normal functioning of the body. It is mainly made by the liver but can also be found in some foods.
Cholesterol is a fat chemical (lipid) that is made in the cells in your body. Many different cells make cholesterol but cells in the liver make about a quarter of the total. Although many foods contain cholesterol, it is poorly absorbed by the gut into the body. Therefore, cholesterol that you eat in food has little effect on your body and blood cholesterol level. A certain amount of cholesterol is present in the bloodstream. You need some cholesterol to keep healthy. Cholesterol is carried in the blood as part of particles called lipoproteins. There are different types of lipoproteins, but the most relevant to cholesterol are:
- Low-density lipoproteins carrying cholesterol – LDL cholesterol. This is often referred to as bad cholesterol. This is the one mainly involved in forming atheroma. Atheroma is the main underlying cause of various cardiovascular diseases (see below). The majority of cholesterol in the blood is LDL cholesterol, but how much varies from person to person.
- High-density lipoproteins carrying cholesterol – HDL cholesterol. This is often referred to as good cholesterol. This may prevent atheroma forming.
WHAT ARE THE DIFFERENT TYPES OF CHOLESTEROL?
Cholesterol does not travel freely through the bloodstream. Instead, it is attached to a protein and the two together are called a lipoprotein (lipo=fat). There are three types of lipoproteins that are categorized based upon how much protein there is in relation to the amount of cholesterol.
Low-density lipoproteins (LDL) contain a higher ratio of cholesterol to protein and are thought of as the “bad” cholesterol. Elevated levels of LDL lipoprotein increase the risk of heart disease, stroke, and peripheral artery disease, by helping form cholesterol plaque along the inside of artery walls. Over time, as plaque buildup increases, the artery narrows (atherosclerosis) and blood flow decreases. If the plaque ruptures, it can cause a blood clot to form that prevents any blood flow. This clot is the cause of a heart attack or myocardial infarction if the clot occurs in one of the coronary arteries in the heart.
High-density lipoproteins (HDL) are made up of a higher level of protein and a lower level of cholesterol. These tend to be thought of as “good” cholesterol because they can extract cholesterol from artery walls and dispose of them in the liver. The higher the HDL to LDL ratio, the better it is for the individual because such ratios can potentially be protective against heart disease, stroke, and peripheral artery disease.
Very low-density lipoproteins (VLDL) contain even less protein than LDL.
Total cholesterol is the sum of HDL, LDL, and VLDL.
WHEN SHOULD I TEST MY CHOLESTEROL LEVELS?
Blood cholesterol levels are measured with a simple blood test. This blood sample will be used to determine the amount of LDL (bad cholesterol), HDL (good cholesterol) and triglycerides (other fatty substances) in your blood.
You may be asked not to eat for 10-12 hours before the cholesterol test (usually including when you are asleep at night). This ensures that all food is completely digested and will not affect the outcome of the test.
Your GP or practice nurse can carry out the cholesterol test and will take a blood sample either using a needle and a syringe or by pricking your finger.
Your GP may recommend that you have your blood cholesterol levels tested if you:
- have been diagnosed with coronary heart disease, stroke or mini-stroke (TIA) or peripheral arterial disease (PAD)
- have a family history of early cardiovascular disease
- have a close family member who has a cholesterol-related condition
- are overweight
- have high blood pressure, diabetes or a health condition that can increase cholesterol levels
Everybody has some risk of developing atheroma which then may cause one or more cardiovascular diseases. However, some situations increase the risk. These include:
- Lifestyle risk factors that can be prevented or changed:
- Lack of physical activity (a sedentary lifestyle).
- An unhealthy diet – including eating too much salt.
- Excess alcohol.
- Treatable or partly treatable risk factors:
- High blood pressure (hypertension).
- High cholesterol blood level.
- High triglyceride (another type of fat) blood level.
- Kidney diseases that affect kidney function.
FIXED RISK FACTORS – ONES THAT YOU CANNOT ALTER
- A strong family history. This means if you have a father or brother who developed heart disease or a stroke before they were 55, or in a mother or sister before they were 65.
- Being male.
- An early menopause in women.
- Age. You are more likely to develop atheroma as you get older.
- Ethnic group. For example, people who live in the UK whose family came from India, Pakistan, Bangladesh or Sri Lanka have an increased risk.
However, if you have a fixed risk factor, you may want to make extra effort to tackle any lifestyle risk factors that can be changed. See separate leaflet called Preventing Cardiovascular Diseases for more details.
Note: some risk factors are more risky than others. For example, smoking and a high cholesterol level probably cause a greater risk to health than obesity. Also, risk factors interact. So, if you have two or more risk factors, your health risk is much more increased than if you just have one.
For example, a middle-aged male smoker who has high blood pressure and a high cholesterol level has a high risk of developing a cardiovascular disease, such as a heart attack, before the age of 60.
If you are at moderate or high risk of developing a cardiovascular disease then treatment with medication is usually advised along with advice to tackle any lifestyle issues. This usually means:
- A medicine to lower your cholesterol level, usually with a statin medicine. No matter what your current cholesterol level, treatment is advised. There are several different statin medicines. They work by blocking a chemical (enzyme) which is needed to make cholesterol in the liver. See separate leaflet called Statins and Other Lipid-lowering Medicines for details.There is no actual target level for people who do not already have cardiovascular disease. However, for those who do have a cardiovascular disease, the aim, if possible, is to reduce TChol to less than 4.0 mmol/L and LDL cholesterol to less than 2.0 mmol/L.
- Treatment to lower blood pressure if it is high. This is even if your blood pressure is just mildly high. See separate leaflet called High Blood Pressure (Hypertension) for details.
In addition, if you already have cardiovascular disease, a daily low dose of aspirin is also usually advised . Aspirin helps to prevent blood clots from forming on patches of atheroma. See separate leaflet called Aspirin and Other Antiplatelet Medicines for details.
IN ADDITION, EVERYONE SHOULD AIM TO TACKLE LIFESTYLE RISK FACTORS. THIS MEANS TO:
- Stop smoking if you smoke.
- Eat a healthy diet.
- Keep your salt intake to under 6 g a day.
- Keep your weight and waist in check.
- Take regular physical activity.
- Cut back if you drink a lot of alcohol.
If available (and if required) you may be offered a referral to a specialist service. For example, to a dietician to help you to lose weight and eat a healthy diet, to a specialist stop smoking clinic, or to a supervised exercise programme.
By Medifit Education.