What is High Cholesterol?
High cholesterol is a condition where you have too much of a fatty substance called cholesterol in your blood. While some cholesterol is essential for building healthy cells, an excess can lead to fatty deposits in your blood vessels, increasing the risk of heart disease and stroke.
Cholesterol is a natural fatty substance produced primarily by the liver and found in some foods. It is vital for the production of hormones, Vitamin D, and the membranes of every cell in your body. However, when levels of certain types of cholesterol become too high, it can begin to collect on the inner walls of your arteries. This process, known as atherosclerosis, can eventually restrict blood flow. This article explains the different types of cholesterol, how they affect your health, and the steps you can take to maintain healthy levels according to the latest UK clinical guidance.
What We’ll Discuss in This Article
- The fundamental definition of cholesterol and its role in the body.
- The critical differences between ‘good’ (HDL) and ‘bad’ (non-HDL) cholesterol.
- An overview of healthy cholesterol ranges and what your test results mean.
- Common causes and lifestyle triggers that lead to elevated levels.
- How high cholesterol is diagnosed and the importance of the QRISK score.
- Evidence-based methods for lowering cholesterol through diet and medication.
What is cholesterol and why does it matter?
Cholesterol is a lipid that travels through the blood attached to proteins; these combinations are called lipoproteins. It matters because high levels of specific lipoproteins are a major risk factor for cardiovascular disease (CVD). If left unmanaged, fatty deposits can break off and form a clot, leading to a heart attack or stroke.
Cholesterol itself is not ‘poison’; your body requires it to function. The liver produces approximately 80% of the cholesterol in your blood, while the remaining 20% comes from the food you eat. Problems arise when there is an imbalance. According to the British Heart Foundation (BHF, 2025), high cholesterol is often a ‘hidden’ risk factor because it typically presents no physical symptoms until a cardiac event occurs.
Understanding LDL vs HDL cholesterol
Cholesterol is categorised based on the lipoprotein that carries it. High-Density Lipoprotein (HDL) is ‘good’ because it carries cholesterol away from the cells and back to the liver to be broken down. Low-Density Lipoprotein (LDL) and other non-HDL types are ‘bad’ because they deliver cholesterol to the cells, where it can build up in artery walls.
The distinction is vital for clinical management. A high level of HDL is actually protective, whereas a high level of non-HDL (which includes LDL) is the primary concern for doctors.
| Type of Cholesterol | Role in the Body | Health Impact |
| HDL (Good) | Transports cholesterol to the liver for removal. | Higher levels reduce cardiovascular risk. |
| Non-HDL (Bad) | Carries cholesterol to the arteries. | Higher levels increase risk of atherosclerosis. |
| Triglycerides | Stores unused calories as fat for energy. | High levels combined with high LDL increase risk. |
What causes high cholesterol?
High cholesterol is most commonly caused by lifestyle factors, such as a diet high in saturated fats and a lack of physical activity. However, it can also be influenced by genetics, age, and underlying health conditions.
The NHS (2025) identifies several primary causes and contributors:
- Dietary Choices: Consuming high amounts of saturated fats (found in fatty meats, butter, and processed foods) changes how the liver processes cholesterol.
- Physical Inactivity: Regular exercise helps increase HDL levels and makes LDL particles less harmful.
- Smoking: A chemical in cigarettes called acrolein stops HDL from taking cholesterol to the liver.
- Genetics: Some people inherit a condition called Familial Hypercholesterolaemia (FH), which causes very high cholesterol from birth regardless of lifestyle.
Triggers and Risk Factors
Certain groups are at a higher risk of developing high cholesterol due to biological triggers. These include being over the age of 40, being of South Asian or sub-Saharan African origin, or going through the menopause.
Secondary causes conditions that ‘trigger’ high cholesterol include:
- Type 2 diabetes.
- Underactive thyroid (hypothyroidism).
- Kidney or liver disease.
- Excessive alcohol consumption.
Differentiation: High Cholesterol vs. High Blood Pressure
While both are ‘silent’ risk factors for heart disease, they affect the body differently. High cholesterol involves the build-up of fat that narrows the pipes (arteries), while high blood pressure (hypertension) is the force of the blood pushing against the walls of those pipes. Often, these two conditions occur together because narrowed arteries require the heart to pump harder, raising blood pressure.
To Summarise
High cholesterol is a manageable but serious risk factor for cardiovascular health. It involves an imbalance of lipoproteins, specifically an excess of non-HDL cholesterol. Because it has no symptoms, regular testing—especially for those over 40—is essential. Management involves a combination of heart-healthy dietary changes, increased activity, and, where necessary, medications like statins to reach the targets set by NICE and the NHS.
If you experience severe, sudden, or worsening symptoms, such as sudden chest pain or difficulty breathing, call 999 immediately.
Does high cholesterol have symptoms?
No, high cholesterol typically has no symptoms; it is usually only detected through a blood test.
Can I lower my cholesterol through diet alone?
For many, lifestyle changes can reduce cholesterol by about 10%; however, those at high risk may also require medication.
What is a healthy total cholesterol level?
As a general guide, total cholesterol should be below 5mmol/L for healthy adults.
What are statins?
Statins are a group of medicines that help lower the amount of Low-Density Lipoprotein (LDL) cholesterol produced by the liver.
Is all fat bad for cholesterol?
No, unsaturated fats (like those in olive oil and nuts) can actually help improve your cholesterol profile.
How often should I get checked?
If you are over 40, you should be offered an NHS Health Check every five years which includes a cholesterol test.
Authority Snapshot (E-E-A-T Block)
This article was written by the MyPatientAdvice Medical Content Team and reviewed by Dr. Rebecca Fernandez to ensure clinical accuracy and adherence to current UK medical standards. Dr. Fernandez is a UK-trained physician with extensive experience in cardiology, internal medicine, and emergency care. This guide covers the biological mechanisms of cholesterol, diagnostic thresholds, and evidence-based management strategies to support public heart health and safety.
