What is high cholesterol?

Cholesterol is a type of blood fat, and we all need some cholesterol in our blood for our bodies to stay healthy. But if your cholesterol levels are too high this can lead to serious health problems in the future, including heart attacks and strokes.

Anyone can have high cholesterol, even if you are young, slim, eat well and exercise. That’s because high cholesterol can be caused by different things. It can be caused by an unhealthy lifestyle, but it can be genetic too.

High cholesterol is very common, but most people don't know they have it, which is why everyone should have a cholesterol check. Another type of blood fat called triglycerides can also become raised and lead to health problems, you can have these checked too. 

If your cholesterol is raised, there are treatments available if you need them. But it's usually possible to lower cholesterol naturally with healthy lifestyle changes.


Find out about coronavirus if you have high cholesterol


What happens if you have high cholesterol?

What does high cholesterol mean?

Cholesterol is a type of blood fat. High levels of cholesterol in your blood can clog up your arteries – the large blood vessels that carry blood around your body. Over time, this can lead to serious problems.

How does cholesterol clog up your arteries?

If you have too much cholesterol in your blood, it can be laid down in the walls of your arteries. Fatty areas known as plaques can form, and these become harder with time, making the arteries stiffer and narrower. This process is called atherosclerosis.

  • Narrowed arteries
    When the arteries become narrower, it’s harder for blood to flow through them. This puts a strain on your heart because it has to work harder to pump blood around your body. Eventually, the heart can become weak and can’t work as well as it should.
  • Blood clots
    Blood clots can form over the fatty, hardened parts of the arteries. The blood clots can block the artery completely, cutting off the blood flow. Bits of the blood clots can break away and become lodged in an artery or vein in another part of the body, which can cause a heart attack or stroke.

What can happen if your arteries become clogged up?

If your arteries become clogged up, the blood can't flow around your body as easily, which can lead to a number of diseases of the heart and blood vessels. 

  • Coronary heart disease (coronary artery disease)
    This is where the arteries have become clogged up and stiff with atherosclerosis. The blood can’t flow around the body and back to the heart easily and blood clots can form. This can lead to chest pain, heart failure, heart attacks and strokes.
  • Angina (chest pain)
    This is a dull, heavy or tight pain in the chest which can spread to the left arm, neck, jaw or back. It happens when the arteries leading to the heart have become narrowed and the heart doesn’t get enough oxygen. The pain can be brought on by exercise, as the heart needs more oxygen.
  • A heart attack
    This is a medical emergency. It happens when an artery leading to the heart becomes completely blocked, often by a blood clot, cutting off the blood supply. Part of the heart muscle quickly dies, but if it’s treated very early the blockage can be removed.

    If you think you or someone you are with is having a heart attack, call 999 straight away. The signs of a heart attack include:
    • a crushing pain in the chest
    • sweating
    • shortness of breath
    • feeling or being sick
    • feeling weak or faint
  • Heart failure
    This is not the same as a heart attack. Heart failure usually happens when the heart has to work too hard to force blood around your body. To start with heart muscle gets bigger to cope with the extra effort, but eventually it becomes too weak and can’t push blood around your body.

    It doesn’t mean your heart is about to stop working but it can cause serious problems including breathing problems – as the blood can’t flow around your lungs easily.
  • Stroke
    This is a medical emergency. It happens when an artery in or leading to the brain becomes blocked, cutting off the blood supply. Part of the brain dies which can cause disabilities. Getting treatment straight away can lower the risk of long-term problems afterwards.

    If you notice the signs of a stroke, in yourself or someone else, call 999 straight away. The signs include:
    • the face droops on one side
    • slurred speech or being unable to talk
    • weakness in the arms or not being able to lift them.
  • Mini strokes (TIAs)
    Blocked blood vessels can also cause mini strokes known as TIAs (transient ischaemic attack). These are temporary, and the signs of a stroke pass within 24 hours, usually after a few minutes. Mini strokes are a warning sign that you could have a full stroke.

    See your doctor straight away if you think you have had a TIA so that you can get treatment and support to prevent a stroke.
  • Peripheral arterial disease (PAD)
    This is when one or more of the arteries leading to the legs and feet become blocked or narrowed, so not enough blood can reach them. This can make your feet feel cold and painful, especially when walking. It can be hard to walk, and the worst-case scenario is that the foot needs to be amputated.
  • Vascular dementia
    There are different types of dementia, and the second most common type is vascular dementia. It can cause problems with memory, thinking and talking. It’s caused by problems with the blood supply to the brain – either by a stroke or mini strokes, or because the blood vessels in the brain have become too narrow.

These diseases of the heart and blood vessels are known together as cardiovascular disease – cardio refers to the heart and vascular refers to the blood vessels.

Treatments and healthy lifestyle changes to lower your cholesterol can help prevent all of these problems or stop them from getting worse.

Find out about coronavirus (COVID-19) if you have heart disease


What causes high cholesterol?

Lots of different things play a part in your cholesterol levels, including your lifestyle, any other health problems you may have, and your genes. And these can all add up.

  • Your overall health
    Your overall health and other health problems can have an effect, for example:
    • being overweight
    • carrying your weight around your middle
    • an underactive thyroid gland
    • type 2 diabetes
    • liver disease
    • kidney disease
    • certain medications.
  • Other things that can affect your cholesterol levels
    There are other things you can't change that can mean you’re more likely to develop high cholesterol or heart disease:
    • your age – raised cholesterol and damaged arteries become more likely with age
    • being male – men are more likely to have high cholesterol and heart attacks than women 
    • South Asian background
    • a close family member, such as a parent, brother or sister, has had high cholesterol, heart disease or a stroke.

Find out your cholesterol level with a cholesterol check


All these causes, or risk factors, can add up to raise your risk of high cholesterol and heart disease.  When you take steps to lower your cholesterol, you can lower your risk of other diseases like type 2 diabetes too. 


Learn more about what can raise your cholesterol and how you can keep your cholesterol levels healthy.

If you are worried about your cholesterol, you can email our Cholesterol Helpline ask@heartuk.org.uk