What do my cholesterol numbers mean?

Who should have a cholesterol test?

Cholesterol is measured by a simple blood test. If you are over 40 and have not had one before, have a heart condition such as high blood pressure, you’re overweight, have diabetes or high cholesterol runs in your family, then you will be eligible for a test on the NHS.

If you’re aged 40 to 74 and do not have a pre-existing health condition, you may be invited by your GP for an NHS health check. These are typically performed every 5 years and include a cholesterol test as well as other relevant checks.

How is cholesterol tested?

A cholesterol test measures the amounts of different types of packaged cholesterol circulating in your blood, in the UK this is measured as mmol/L and there are two methods:

• A blood draw from the arm – a blood sample will be taken from your arm and sent to a lab for analysis. You should get the results in a few days. You may be asked to fast (not eat for 12 hours) before the test, but for most people this is not necessary.
• A finger prick test – the NHS health check (for the over 40s) is sometimes available from pharmacies and a finger prick test may be used. The test is done by pricking a finger and collecting the blood on a strip of paper, this is put into a machine and your results are available in a few minutes.

What do my cholesterol numbers mean?

The first thing to know about cholesterol is that cholesterol doesn’t move through your body freely, it has to be carried by particles known as lipoproteins. These lipoproteins carry cholesterol and other fats through the blood to various destinations. What determines whether a lipoprotein is ‘good’ or ‘bad’ isn’t actually the cholesterol at all but the type of lipoprotein that binds with the cholesterol to transport it.

There are various types of lipoproteins but the most talked about are low density lipoprotein (LDL) which contains apolipoprotein B (ApoB) and high-density lipoprotein (HDL) which contains apolipoprotein A (ApoA). All lipoproteins carry cholesterol and other fats, just in different proportions. This means when we are referring to cholesterol being carried it is more accurate to refer to it as LDL-cholesterol (LDL-C) and HDL-cholesterol (HDL-C).

Starting in the liver, where most cholesterol is produced, LDL carries it all over the body, including to our arteries. If there is too much LDL-C or the particles are small, they can become deposited in the arteries, leading to plaque build-up. This is why LDL-C has a ‘bad’ reputation. HDL particles do the reverse and pick up excess cholesterol including from your arteries and transport it back to the liver – this is why HDL-C is often referred to as ‘good’.

What is a healthy cholesterol level?

The following is a guide for a healthy, average adult. If you have been ill, are on prescribed medication or have recently had a baby your levels may be higher or lower than this, there are also a number of other factors that may influence your result, including the time of year that the test is taken.

• Total or serum cholesterol– refers to all the cholesterol measured in your blood, anything greater than 5mmol/L would be considered raised.
• HDL-C – the amount of cholesterol being transported by high density lipoproteins. For men, the aim is to be above 1.0mmol/L and for women, above 1.2mmol/L. Experts consider levels of up to 1.4mmol/L to be protective.
• Total – HDL-C ratio is used for the QRISK calculation (see below.) iIt does, however, need careful interpretation because if you have high levels of HDL, the ratio may fall within the normal range even though non-HDL levels are high. Guidance suggests this should be below 4.
• Non-HDL-C – this is effectively all of the different types of unfavourable cholesterol (mainly LDL). It is calculated by subtracting your HDL from your total cholesterol - the result should be below 4mmol/L, but ideally as low as possible.
• LDL-C – this is an estimation of the amount of cholesterol being transported by low density lipoproteins. Guidance suggests this should be below 3.0mmol/L.
• Triglycerides – these are another type of blood fat, if your levels are high, you are more likely to have a low HDL. A fasting result (a test taken when you haven’t eaten for 12 hours) should ideally be below 1.7mmol/L, a non-fasting result 2.3mmol/L.

In the past, you may have been advised to fast (refrain from eating for 12 hours) before a cholesterol test. However, this guidance has now changed, although many argue that a fasting test is likely to be more representative, especially for those with certain conditions, such as type II diabetes or who are prescribed certain medications. What's more, recent research suggests that a more accurate picture of the levels of so-called ‘bad’ cholesterol might be achieved by testing for the ApoB protein in the blood. Currently on the NHS this test is only available to people with a significant family history of coronary artery disease or with abnormal LDL-C results.

If your medical practitioner only gives you a total cholesterol result, ask for a break-down of the other numbers. This is important because it is possible to have a ‘healthy’ total cholesterol but a less favourable balance of the other classifications.

How is my risk of a heart attack or stroke calculated?

Your GP may talk to you about your risk of having a heart attack or stroke over the next 10 years. This is calculated using a tool called QRISK. The tool takes into account your cholesterol levels, age, gender, ethnicity, as well as whether you smoke, have high blood pressure or are overweight. It arrives at a percentage score – the higher the percentage, the greater your risk. In the UK, anyone with a risk higher than 10% should be offered interventional treatment including lifestyle modifications, blood pressure management or cholesterol lowering medication.

How often should you test your cholesterol?

The NHS recommends a test every five years unless you have a condition that may require more frequent monitoring – such as a diagnosis of high cholesterol or if you take medication that affects your cholesterol levels.

What are the symptoms of high cholesterol?

High cholesterol is largely symptomless and, if left undiagnosed, may lead to a heart attack or stroke. Lifestyles factors that suggest you are at an increased risk include obesity, inactivity, smoking, heavy alcohol consumption and poor sleep as well as high levels of stress.

Those with familial hypercholesterolemia may have symptoms such as cholesterol deposits in the skin or on the eyelids, yellow areas around the eye or a pale ring on the iris, or deposits in a half-moon shape on the cornea. Other symptoms include swollen tendons or bumps around joints, like the knuckles.

5 ways to lower high cholesterol

There are a number of ways to help manage your cholesterol levels, these include:

• Scale back foods rich in saturated and trans fats, instead eat more healthy fats including omega-3 fats as they increase the size and density of LDL particles making them less likely to stick to the artery walls. Find them in oily fish, like sardines and salmon, as well as nuts and seeds
• Minimise the refined carbs and sugars in your diet and opt for wholegrain versions of bread and pasta instead. Also, eat more foods rich in a soluble form of fibre such as oats and flaxseeds, these help the body remove excess cholesterol
• Increase the plant foods in your diet, these include beans and pulses. Studies suggest those following a plant-focused diet may improve their LDL-C levels
• Certain foods, like avocado, are rich in compounds called plant stanols and sterols, these may help inhibit the absorption of cholesterol in the gut
• Eat an abundant variety of vegetables and fruit – these may help protect LDL-C particles from the damaging effects of a natural process called oxidation, which may lead to plaque formation.
• Incorporate regular cardio-based exercise and strength training into your routine, this may improve HDL-C levels
• If you smoke or vape, stop
• If you enjoy an alcoholic tipple, be sure to keep within government guidelines
• Achieve and maintain a healthy weight for your height, age and gender

Your GP may recommend a medication such as a statin, this may be suggested because the steps you’ve taken to change your diet and lifestyle are not working, you have a genetic disorder that raises your risk or because of your age.

Are your cholesterol numbers healthy?

Although we commonly talk about lowering cholesterol, the aim should really be to achieve the right balance for you. Knowing your figures is a useful first step – your age, gender, family history and medical background also play a part in determining what level is appropriate. Don’t forget, even the time of year that your test was taken, and whether you fasted or not, may influence your figures.

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Kerry Torrens BSc. (Hons) PgCert MBANT is a Registered Nutritionist with a post graduate diploma in Personalised Nutrition & Nutritional Therapy. She is a member of the British Association for Nutrition and Lifestyle Medicine (BANT) and a member of the Guild of Food Writers. Over the last 15 years she has been a contributing author to a number of nutritional and cookery publications including BBC Good Food. Find her on Instagram at @kerry_torrens_nutrition_

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