Healthy Levels of Cholesterol

By Dietitian, Juliette Kellow BSc RD

Q I recently heard a friend talking about ‘good’ and ‘bad’ cholesterol. I thought there was just one type of cholesterol. Can you explain more?

A Cholesterol is a fat-like substance that’s made mainly in the liver and is an essential part of every cell. Your friend is right though. There are two main types of cholesterol that doctors and dietitians talk about: LDL or ‘bad’ cholesterol, high levels of which are linked to heart disease; and HDL or ‘good’ cholesterol, high levels of which are thought to protect against heart disease.

LDL cholesterol is carried to the body’s cells, where the cells take as much cholesterol as they need, leaving any excess in the blood. If there’s constantly too much bad cholesterol left in the blood it can build up in the arteries, eventually causing blockages or breaking away to form clots – this is why it’s often referred to as ‘bad’ cholesterol.

In contrast, HDL cholesterol is extra cholesterol from the tissues that gets carried away from the arteries to the liver where the body gets rid of it. This type is important for a healthy heart as it’s the cholesterol that’s eliminated from the body – hence the reason it’s sometimes referred to as ‘good’ cholesterol.

Usually, when you have your blood cholesterol measured, your GP will look at figures for your overall or total cholesterol level, plus figures for your LDL and HDL cholesterol. Healthy levels of cholesterol are as follows:

• Total cholesterol – less than 5 mmol/L
• LDL cholesterol – less than 3 mmol/L
• HDL cholesterol – more than 1 mmol/L

When it comes to lowering cholesterol, it’s particularly important to lower LDL cholesterol as this is the type that increases the risk of heart disease, while maintaining or increasing levels of HDL cholesterol. This can usually be achieved through changing your eating habits, losing weight and exercising regularly. My Low Cholesterol Diet answer gives more information about this.