What is cholesterol?

Cholesterol is a fatty substance which is made in the liver. It’s found in some foods too. We all need some cholesterol in our bodies just to keep us ticking over but having too much can clog up your arteries and lead to health problems in the future.

By getting a simple cholesterol test and making positive lifestyle changes, most people can keep their cholesterol levels healthy.

Why do we need cholesterol?

Cholesterol plays a vital role in how your body works. There is cholesterol in every cell in your body, and it's especially important in your brain, nerves and skin.

Cholesterol has three main jobs:

  • It’s part of the outer layer, or membrane, of all your body’s cells
  • It’s used to make vitamin D and steroid hormones which keep your bones, teeth and muscles healthy
  • It’s used to make bile, which helps to digest the fats you eat

If you have a question, email the Cholesterol Helpline to get in touch.  ask@heartuk.org.uk

Cholesterol levels for men and women

  • Women naturally have higher HDL cholesterol (good cholesterol) levels than men. This is due to differences in the genes. Women should aim for an HDL cholesterol level above 1.2mmol/L while men should aim for above 1mmol/L. Find out what your other cholesterol levels should be. 
  • During pregnancy, both cholesterol and triglyceride levels can significantly rise.  At HEART UK we don't recommend getting a cholesterol test during pregnancy because your results wont be accurate. Our advice is to wait until at least three months after your baby is born to get a cholesterol test. This means you don't need to worry unnecessarily. 

    Women may also find their cholesterol levels rise during the menopause. 

 

Where is cholesterol made?

Some of our cholesterol comes from the food we eat, but most is made in the liver.

After a meal, the fat in your food is broken down into triglycerides. These triglycerides are absorbed into the blood from the intestines and transported around the body. Cholesterol and triglycerides cannot circulate loosely in the blood, so the liver packages them into  “parcels” called lipoproteins.

The lipoproteins are then released into the blood and carried around the body to wherever they're needed. You can read more about the different types of lipoproteins below. 

How is cholesterol broken down?

Some cholesterol will be returned to the liver and broken down. It’s used to make bile acids which are released into the intestines to help with digestion. They break down fats in food.

A small amount of bile acids will be removed from the body as a waste product. But most will be absorbed back into the blood, returned to the liver and used again for digestion.

Some treatments for high cholesterol work by stopping bile from being absorbed back into the blood. So, the liver has to take more cholesterol out of the blood to make more bile, lowering your cholesterol levels.

Triglycerides

There is another type of blood fat called triglycerides.

Triglycerides enter the blood stream after a meal. They are also made by your liver. Triglycerides are packaged into lipoproteins along with cholesterol. When they reach the cells throughout your body, they’re used for energy or stored for later.

A high triglyceride level in your blood should be investigated by your GP. There can be many reasons for a high triglyceride level and it's important to find out the exact cause. A raised level can add to your overall risk of developing heart disease, and if they're very high they can cause other serious problems such as pancreatitis. 

Find out about the different reasons for a high triglyceride level

It's useful to have your triglycerides tested when you get a cholesterol check.

Read more about triglycerides

 

What raises your cholesterol?

Your blood fats – your cholesterol and triglycerides – can become raised for a number of reasons.

For example:

  • a diet which is high in saturated fats
  • not being active enough, so the fats aren't used up for energy
  • genetic conditions which mean the fats aren't processed in the usual way.

What if I have high cholesterol?

 

  • saturated fats
  • low activity
  • genetic conditions

What are the different types of cholesterol?

Cholesterol is a type of blood fat – blood fats are known as lipids. Cholesterol is carried in the blood from the liver, where it’s made, to wherever it’s needed in the body. It’s carried attached to proteins and other fats, and together they form tiny spheres, or balls, known as lipoproteins – lipids plus proteins.

There are two main types of lipoproteins. When people talk about the different types of cholesterol, they’re usually talking about these lipoproteins:

  • LDL Cholesterol (low density lipoprotein)
    This is often called bad cholesterol, because too much in the blood can lead to health problems. They contain lots of cholesterol. LDL cholesterol's job is to deliver cholesterol to the cells where it’s needed. But if there’s too much it can build up in the arteries, clogging them up.
  • HDL Cholesterol (high density lipoprotein)
    This is often called good cholesterol because it helps your body stay healthy and prevents disease. They contain lots of protein, and very little cholesterol. HDL cholesterol’s job is to carry cholesterol away from the cells, back to the liver, where it can be broken down and removed from the body.

 

There are other types of lipoproteins too:

  • VLDL (very low density lipoproteins)
    These are larger. They carry another type of fat called triglycerides, plus some cholesterol, from the liver around your body. They contain lots of fat and very little protein. If there is too much VLDL in your blood, fat can be laid down in your artery walls, clogging them up. 
  • IDL (Intermediate density lipoproteins)
    These carry cholesterol and triglycerides. They are between LDL and VLDL cholesterol in terms of how much fat they carry. These are in fact VLDL lipoproteins after some of the triglycerides have been taken out of them. 
  • Chylomicrons
    These are the largest lipoprotein. They carry triglycerides from the gut to the liver after a meal, where they are broken down, and the fats are repackaged into the other lipoproteins.

 

Why should I get a cholesterol test?

High cholesterol usually doesn’t have any symptoms, so you won’t know if you have it. The first sign of it can be a heart attack.

There are different causes of high cholesterol – it can be to do with your lifestyle, but it can be genetic too. So even if you are young, fit, slim and otherwise healthy you could still have high cholesterol.

A simple blood test can show you how much of the different types of cholesterol you have in your blood. This can give an idea of your risk of heart disease and stroke. It can show if you need to make any healthy changes or have any treatments to bring your cholesterol under control.

The blood test is very quick and easy. It's usually a finger prick test where you feel a tiny pinch as a small amount of blood is taken. Your doctor or nurse can check your cholesterol level there and then.