What is it?
Cholesterol is a fatty substance found naturally in the blood. Despite its reputation, the body needs it — it plays an essential role in building healthy cells, producing hormones, and absorbing fat-soluble vitamins. The problem arises when there is too much of certain types circulating in the bloodstream.
Cholesterol is carried through the blood by proteins, forming particles called lipoproteins. There are three key types:
| Type | Common name | What it does |
|---|---|---|
| LDL (low-density lipoprotein) | "Bad" cholesterol | Deposits cholesterol into artery walls, forming plaques that narrow and harden arteries — the main driver of heart attack and stroke risk |
| HDL (high-density lipoprotein) | "Good" cholesterol | Carries cholesterol away from artery walls back to the liver, where it is broken down and removed — a protective process |
| Non-HDL cholesterol | Total minus HDL | The broader measure of all potentially harmful fats — now the preferred treatment target in UK clinical guidelines (NICE NG238) |
Raised cholesterol causes no symptoms. The only way to establish lipid levels is through a blood test — which is why it is categorised alongside hypertension as a clinically silent cardiovascular risk factor.
📖 Key Terms
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Why does it matter?
High LDL cholesterol directly drives the narrowing and hardening of arteries — the process that underlies most heart attacks and strokes. The clinical significance of this relationship is supported by decades of randomised trial data and further confirmed by genetic studies showing that naturally lower LDL from birth is associated with proportionally reduced lifetime cardiovascular risk.
Like hypertension, raised cholesterol produces no symptoms. It is a laboratory finding, not a clinical one — which is why cholesterol testing in the context of routine cardiovascular risk assessment is an established part of UK healthcare practice.
What your doctor might do
Cholesterol testing
Cholesterol is measured through a simple blood test — typically as part of an NHS Health Check (offered to everyone aged 40–74 in England every five years), or when cardiovascular risk factors are present that warrant earlier assessment. The test measures total cholesterol, HDL, and triglycerides, from which non-HDL and LDL are calculated.
Under current UK guidelines (NICE NG238), fasting is not routinely required before a cholesterol blood test, though specific clinical circumstances may affect this.
Understanding the results
Cholesterol numbers are interpreted in the context of overall cardiovascular risk — not in isolation. General targets for most healthy adults in UK practice are:
| Measure | General target (healthy adults) |
|---|---|
| Total cholesterol | Below 5.0 mmol/L |
| Non-HDL cholesterol | Below 4.0 mmol/L |
| LDL cholesterol | Below 3.0 mmol/L |
| HDL cholesterol (men) | Above 1.0 mmol/L |
| HDL cholesterol (women) | Above 1.2 mmol/L |
For those with established cardiovascular disease, treatment targets are lower — below 2.0 mmol/L for LDL, or below 2.6 mmol/L for non-HDL, as set out in NICE NG238.4 Overall risk is assessed using a validated risk calculator (see the risk calculators section of helf.school).
Management — lifestyle and medication
For many people, lifestyle measures produce meaningful improvements in cholesterol profile — reducing saturated fat intake, regular aerobic exercise, weight management, reduced alcohol intake, and smoking cessation are all clinically recognised as beneficial for lipid levels.
Where medication is indicated, statins are the most evidenced first-line treatment. NICE NG238 identifies atorvastatin as first-line for primary prevention in those with a 10-year cardiovascular risk of 10% or more. For those with established cardiovascular disease, the dose is higher. Where statin therapy is not tolerated, ezetimibe and other agents are available options.4
Cholesterol levels are typically rechecked around three months after starting or adjusting treatment to assess the response.
What the research shows
| Treatment | LDL change vs placebo |
|---|---|
| Rosuvastatin (statin) | ~38% reduction |
| Fish oil | No significant reduction |
| Garlic | No significant reduction |
| Cinnamon | No significant reduction |
| Turmeric | No significant reduction |
| Plant sterols | No significant reduction |
| Red yeast rice | No significant reduction |
Cholesterol is one of the most common and most consequential modifiable cardiovascular risk factors in the UK. Around 59% of adults in England have raised total cholesterol — and yet, like blood pressure, it produces no symptoms and is detectable only through testing. The clinical significance of LDL cholesterol as the primary driver of atherosclerosis is supported by large-scale randomised trial evidence and confirmed by genetic data showing that lower lifetime LDL exposure translates to lower lifetime cardiovascular risk.
The evidence for statin therapy is among the most robust in cardiovascular medicine. The SPORT trial confirmed what clinical guidelines have long reflected — no supplement provides the LDL reduction that a statin delivers. Lifestyle measures are genuinely effective as part of a broader approach, and for some people are sufficient at lower risk levels.
Understanding what cholesterol is, what the different numbers mean, and how the evidence supports different management approaches is the foundation for any informed conversation about lipid levels — whether at an NHS Health Check, following a blood test result, or after a diagnosis of cardiovascular disease. That conversation belongs with a GP or healthcare professional.