What is cholesterol?

If you’ve recently had a heart attack, your medical team may have talked to you about your cholesterol levels. Here we explain what cholesterol is and some things that may help you bring down your level.

What is cholesterol? 1

Cholesterol is a waxy substance the liver makes from fatty foods you eat. It’s known as a lipid. Lipids are vital as your body needs them to build all its cells. 

The globules that carry cholesterol through your bloodstream have a slippery coating to stop them from sticking to the linings of blood vessels. But if you have high levels of cholesterol in your blood, this coating wears off – so the cholesterol is more likely to stick to the blood vessels like the coronary arteries, putting you at more risk of heart attack.

'Good and ‘bad’ cholesterol 1

There are two types of globules that carry cholesterol around your blood.

Low-density lipoprotein (LDL) is known as ‘bad’ cholesterol. It carries cholesterol from your liver to wherever it’s needed in your body. If your blood has too much LDL cholesterol, it can harm your arteries.

High-density lipoprotein (HDL) is known as ‘good’ cholesterol. Its job is to clean up cholesterol from the arteries and take it back to the liver to be recycled – so it reduces the risk of your arteries clogging up.

Generally, cholesterol levels should be no higher than 5mmol/L, with a healthy ratio of HDL and LDL of around 2/1. But if you’ve had a heart attack, the aim is for cholesterol to be no higher than 4mmol/L.

What causes high cholesterol? 1

Eating saturated fat increases ‘bad’ LDL cholesterol. Foods that are high in saturated fat include butter and lard, hard cheese, red meat, meat pies and sausages, biscuits, cakes, pastry and cream. 

Not being active enough and being overweight can also raise levels of LDL (‘bad’) cholesterol and lower HDL (‘good’) cholesterol.

Is high cholesterol in my genes? 2

Cholesterol levels do vary from person to person and this is due to a combination of lifestyle and genes that we inherit. But it is thought that around one in 250 people have Familial Hypercholesterolaemia, a genetic condition that means even with an extremely healthy diet and lifestyle they have very high cholesterol levels 3.  If you have very high cholesterol or a strong family history of cardiovascualr disease, this is something that may be discussed with you and tested for.

What foods can help reduce cholesterol? 4

  • Fruits and vegetables naturally contain plant sterols, which reduce the amount of cholesterol you absorb.
  • Olive oil is a good substitute for saturated fat as a source of healthy-fats that don’t increase LDL cholesterol and maintains a good HDL/LDL balance.
  • Oily fish, such as salmon, fresh tuna, herring, sardines and trout contain omega 3 fatty acids. Eaten at least once per week, these will help keep membranes fluid. As keeping membranes fluid is also one of cholesterol’s roles, eating omega 3s can help prevent your body from manufacturing more cholesterol to do this job.
  • Oats are high in soluble fibre, and can help lower ‘bad’ cholesterol levels.


Making some changes to your diet can help you manage cholesterol levels. Read our heart-healthy diet tips

1https://www.nhs.uk/conditions/high-cholesterol/, Accessed November 2018

2https://www.nhs.uk/conditions/high-cholesterol/causes/, Accessed November 2018

3Bouhairie, V. E., & Goldberg, A. C. (2015). Familial hypercholesterolemia. Cardiology clinics, 33(2), 169-79.

4https://www.bhf.org.uk/heart-health/risk-factors/high-cholesterol, Accessed November 2018