- Diseases, Disorders & Conditions
Your Cholesterol Numbers Explained
What is Cholesterol?
Cholesterol is a fatty substance found in our foods but mainly made naturally by the body. It’s not the bad thing that you might believe it to be as it does a lot of useful things in the body, such as forming a building block for our hormones.
Good cholesterol vs bad cholesterol.
When cholesterol is carried round the body in the blood, it uses a protein. The cholesterol + protein combo is called a lipoprotein. There are 2 types of these lipoproteins:
LDL (low-density lipoprotein) is the ‘bad’ cholesterol and is more harmful to the body than
HDL (high-density lipoprotein) which is the good cholesterol and has a more protective effect to the body.
Having too much bad cholesterol in the blood can increase your risk of heart disease and this risk is higher if you have a low level of HDL – the good cholesterol. So the ratio between the 2 is important.
High LDL cholesterol puts you at more risk of heart disease and heart attacks by putting fatty deposits in the heart’s arteries, blocking them.
What are triglycerides ?
Another type of fatty substance in the blood are the triglycerides. They come from the diet – dairy produce and meat contain a lot of triglycerides – but can also be produced in the liver or from the body’s fat stores.
Therefore, people who eat a lot of fatty and sweet foods, who are overweight or drink too much alcohol often have a high triglyceride level.
These high levels are also a risk factor for heart disease and heart attacks.
What are normal cholesterol levels?
Cholesterol levels are measured either by taking a blood test from a vein in the arm or by a finger-prick blood test and putting it into a desktop analyser.
In the UK the measurement is in millomols per litre (of blood) and is often written as ‘mmol/l’.
Normal cholesterol levels for the UK are as follows:
- a total cholesterol level under 4 mmol/l
- an LDL cholesterol level under 2 mmol/l (bad cholesterol)
- an HDL cholesterol level above 1 mmol/l (good cholesterol)
- a triglyceride level less than 1.7 mmol/l.
In the US cholesterol levels are measures in milligrams per decilitres, written as mg/dL
Normal cholesterol levels for the US are as follows:
- a total cholesterol level less than 200mg/dL
- an LDL cholesterol level under 200mg/dL (bad cholesterol)
- an HDL cholesterol level above 60mg/dL (good cholesterol)
- a triglyceride level less than 150 mg/dL.
Cholesterol levels can vary quite a lot so your doctor will usually make a decision about whether you need cholesterol lowering drugs after looking at a series of readings.
Cholesterol levels are also a contributor to heart disease and heart attacks.
Why have I got high cholesterol?
The most common cause of having raised levels of cholesterol in the blood is through eating it in the diet. Too much saturated fat, found in dairy products and red meat, is a major source.
It used to be thought that foods like eggs, offal (liver, kidneys) and some seafood (prawns for example) were high cholesterol foods. This is now not thought to be the case and it is more important to cut the amount of saturated fat that you eat.
Another reason for having high cholesterol, often despite a healthy, low fat diet, is because of a condition called Familial Hyperlipidaemia (FH). This condition is passed on in families and causes the cholesterol to be raised to very high levels.