Cholesterol is one of the most talked-about numbers in health and one of the least understood. This guide explains what it is, what the figures on a blood test report mean, and what NHS and British Heart Foundation advice says can lower it.
What is cholesterol, and why does it matter?
According to the NHS, high cholesterol means having too much of a fatty substance called cholesterol in the blood. Your body needs some cholesterol to work normally, so the aim is not to remove it. The concern is an excess: too much can block blood vessels, which raises the risk of heart problems and stroke.
The British Heart Foundation (BHF) explains that cholesterol travels around the body attached to proteins. Two types matter most in everyday conversation:
- HDL cholesterol, often called “good” cholesterol, takes unneeded cholesterol back to the liver, which breaks it down so it can leave the body.
- Non-HDL cholesterol, often called “bad” cholesterol, carries cholesterol from the liver to cells around the body. Too much can build up in artery walls. It is mostly made up of LDL cholesterol.
Triglycerides are a separate blood fat. The BHF notes that high levels can narrow arteries and are linked to excess weight, saturated fat, sugar and alcohol.
Why don’t most people notice high cholesterol?
Both the NHS and the BHF are clear that high cholesterol usually causes no symptoms. That is why it is sometimes described as a hidden risk factor. You can feel entirely well and still have levels that put extra strain on your blood vessels over the years.
The same is true of high blood pressure, which we cover in our guide to blood pressure numbers and what they mean. Neither condition announces itself, which is why testing matters more than waiting for warning signs.
How is cholesterol tested?
The NHS describes two main routes:
- An arm blood test. Blood is taken from your arm and sent to a laboratory, with results usually available within a few days. You may be asked to fast for up to 12 hours beforehand, although most people do not need to.
- A finger-prick test. A drop of blood is placed on a strip and read by a machine, giving a result within minutes. This is offered during an NHS Health Check for people over 40, or at a pharmacy, where you may have to pay.
According to the NHS, you can ask your GP surgery for a test if you have not had one before and you are over 40, overweight, or have a family history of high cholesterol or heart problems. The BHF adds that adults in England are offered a free NHS Health Check at 40, and our explainer on what happens at an NHS Health Check covers what to expect.
A full lipid profile, according to the BHF, measures HDL, non-HDL, the cholesterol ratio, triglycerides and total cholesterol, and your GP may also check LDL.
What do the numbers on the report mean?
Results are given in millimoles per litre (mmol/L). The NHS lists the following general levels for healthy adults:
| Measure | General healthy level (NHS) |
|---|---|
| Total cholesterol | Below 5 mmol/L |
| Non-HDL cholesterol | Below 4 mmol/L |
| HDL cholesterol (men) | Above 1.0 mmol/L |
| HDL cholesterol (women) | Above 1.2 mmol/L |
These are guides, not personal targets. The NHS stresses that your GP sets a target based on your age, health conditions and cardiovascular risk, and that levels can differ if you have been ill, are taking certain medicines or have recently had a baby. The BHF also notes that targets may be stricter for people who have already had a heart attack or stroke.
A single number rarely tells the whole story. If your cholesterol is high, the NHS says a doctor or nurse will discuss ways to lower it and may estimate your risk of a heart attack or stroke over the next 10 years. That estimate, rather than cholesterol alone, usually shapes what is recommended.
Who is more likely to have high cholesterol?
Several things can contribute, and some are not within anyone’s control. The NHS lists eating fatty food, not exercising enough, being overweight, smoking and drinking alcohol. It also says the following groups are more likely to be affected:
- people over 50
- men
- people who have been through the menopause
- people of South Asian or sub-Saharan African origin
The BHF adds that a family history of early heart attack or stroke (before the age of 60) matters, as do conditions including kidney disease, liver disease, type 2 diabetes and an underactive thyroid.
What is familial hypercholesterolaemia?
Familial hypercholesterolaemia (FH) is an inherited cause of high cholesterol that, according to the NHS, starts at a young age. It runs in families and is not caused by lifestyle. If close relatives had heart problems early in life, it is worth mentioning this to your GP so that testing can be considered.
Which lifestyle changes can lower cholesterol?
Lifestyle changes are the first line of advice, and the NHS and BHF broadly agree on what they involve.
Food. The NHS suggests cutting down on fatty food, especially saturated fat, and choosing unsaturated fats instead. It recommends eating more oily fish such as mackerel and salmon, olive and rapeseed oils, brown rice, wholegrain bread, wholewheat pasta, nuts, seeds, fruit and vegetables. It suggests eating less of meat pies, sausages, fatty meat, butter, lard, ghee, cream, cheese, cakes, biscuits and foods containing coconut or palm oil. The BHF gives practical swaps, such as olive spread instead of butter, or fish instead of meat. Activity. The NHS advises at least 150 minutes of moderate activity or 75 minutes of vigorous activity a week, with walking, swimming and cycling as starting points.
Alcohol. The NHS says to avoid regularly drinking more than 14 units a week, to spread any drinking over three or more days, and to have several alcohol-free days. Our guide to alcohol units and practical ways to cut back explains how to count them.
Smoking. The NHS notes that smoking can raise cholesterol and increases the risk of heart attacks, strokes and cancer. Support is covered in stopping smoking: NHS support and what to expect.
How strong is the evidence, and what do statins do?
The advice above is mainstream, consistent across the NHS and BHF, and widely accepted. What it cannot do is promise a particular drop in your own cholesterol. Responses vary, and for some people, such as those with FH, diet and exercise alone are unlikely to be enough.
For that reason some people are offered medicine. According to the NHS, statins are offered to people at higher risk of cardiovascular disease when lifestyle changes have not helped or are unlikely to help alone, and to people who already have cardiovascular disease. Higher risk may be indicated by a risk score, by conditions such as diabetes, chronic kidney disease or FH, or by being 85 or over. The NHS explains that statins lower the cholesterol your body makes, and that they are usually taken long term.
Common side effects listed by the NHS include headaches, dizziness, feeling sick, tiredness, flatulence, constipation or diarrhoea, muscle pain and sleep problems. Serious side effects are rare. If you notice side effects, the NHS advises talking to a doctor, who will check the cause and may offer a different statin or change the dose. Statins are not suitable for everyone: the NHS says people who are pregnant or trying to conceive should not take them, and that grapefruit and some other medicines can interact with them.
Statins are prescribed medicine, so do not stop taking them without speaking to a doctor or pharmacist first, as your cholesterol may be affected. The BHF adds that lifestyle changes are usually still needed alongside medicine, with a yearly blood test to monitor progress.
When should you speak to a GP or NHS 111?
Because high cholesterol has no symptoms, there is no symptom to wait for. Consider booking a test with your GP surgery if you are over 40, overweight, or have a family history of high cholesterol or heart problems, or if you have not been tested and have conditions such as high blood pressure or diabetes.
Speak to your GP if you have a close relative who had a heart attack or stroke before 60, or if you take a statin and think you are having side effects. Use NHS 111 for advice if you are unsure whether a side effect is serious. If you have sudden chest pain, signs of a stroke or severe breathlessness, call 999.
A number worth knowing, not worrying about
Cholesterol is a risk factor, not a diagnosis of illness, and a high reading is something you can act on. A test, a look at the lifestyle factors you can change and, where needed, a conversation about medicine are all sensible steps. Knowing your figures puts you in a better position to make those decisions alongside a health professional.
This article is general information, not a substitute for advice from a doctor or other qualified health professional. If you are worried about your cholesterol or heart health, speak to your GP or call NHS 111.
Sources: NHS; British Heart Foundation
