"Your cholesterol is high." Four words that send many patients into a spiral of butter avoidance and egg-counting. And while diet does matter, the reality of cholesterol is considerably more nuanced than the public conversation suggests. Most of what people think they know about cholesterol is either incomplete or outright wrong.
Let me start with the most important fact: total cholesterol is almost meaningless as a standalone number. What matters is the composition — specifically the ratio of LDL to HDL, the presence of other risk factors, and your overall cardiovascular risk profile. A total cholesterol of 6.5 in a 35-year-old woman with no other risk factors is a very different clinical picture from the same number in a 58-year-old man with diabetes and hypertension who smokes.
What the numbers mean — a proper breakdown
When your GP gives you a cholesterol result, they should give you a full lipid profile, not just total cholesterol. Here is what each component means:
| Component | What it is | Target |
|---|---|---|
| Total cholesterol | All cholesterol combined | Below 5.0 mmol/L |
| LDL cholesterol | "Bad" — deposits in artery walls | Below 3.0 mmol/L (lower for high-risk patients) |
| HDL cholesterol | "Good" — removes cholesterol from arteries | Above 1.0 (men) / 1.2 (women) mmol/L |
| Triglycerides | Blood fats, affected by diet and alcohol | Below 1.7 mmol/L |
| Non-HDL cholesterol | Total minus HDL — increasingly used | Below 4.0 mmol/L |
| Total:HDL ratio | Combined risk marker | Below 4.0 |
LDL is the number that most directly correlates with cardiovascular risk. HDL is protective — higher is better. Triglycerides are influenced heavily by diet, alcohol, and diabetes control.
What actually causes high cholesterol
This is where most people get confused, because the answer is: mostly genetics, not diet.
Approximately 75–80% of your blood cholesterol is made by your liver. The remaining 20–25% comes from dietary cholesterol. This is why dietary changes alone typically reduce LDL by only 5–15% — they are addressing a minority of the source.
The main causes:
Familial hypercholesterolaemia (FH): A genetic condition affecting approximately 1 in 250 people in the UK, causing very high LDL from birth regardless of diet. Often diagnosed incidentally or after a cardiovascular event. Requires medication — diet alone is insufficient.
General genetic predisposition: Beyond FH, many people simply inherit a tendency to produce more LDL. This is the most common reason for elevated cholesterol in otherwise healthy people.
Diet: Saturated fat (not dietary cholesterol, as previously thought) raises LDL in most people. Trans fats (largely removed from processed foods in the UK but still present in some) raise LDL and lower HDL — the worst combination.
Lifestyle factors: Physical inactivity lowers HDL. Obesity raises triglycerides and LDL. Smoking lowers HDL.
Secondary causes: Hypothyroidism, type 2 diabetes, kidney disease, liver disease, and some medications (steroids, certain blood pressure drugs) can all raise cholesterol. These must be ruled out before treating elevated cholesterol as a primary condition.
Case study: Emmanuel's confusing result
Emmanuel, 44, a teacher from Ghana based in Manchester, was told at a health check that his total cholesterol was 6.8 and was advised to "cut out fatty foods." He did — meticulously. For eight months he avoided all visible fat, stopped eating eggs, switched to low-fat everything. He repeated the blood test.
Total cholesterol: 6.4. A modest reduction. His GP expressed disappointment.
When I reviewed his full lipid profile: his LDL was 4.2, but his HDL was 1.9 — excellent. His total:HDL ratio was 3.4 — well within the healthy range. His triglycerides were 0.8 — very low.
In context, his cardiovascular risk was not elevated. His total cholesterol looked concerning in isolation but his profile was actually protective. He had spent eight months unnecessarily restricting his diet based on an incomplete picture.
This is why total cholesterol alone tells you so little.
QRISK — your actual cardiovascular risk score
Rather than treating cholesterol numbers in isolation, the UK now uses a tool called QRISK3 to calculate your 10-year risk of a cardiovascular event (heart attack or stroke). It incorporates:
- Age and sex
- Total:HDL cholesterol ratio
- Blood pressure
- Smoking status
- Diabetes
- Family history of cardiovascular disease
- Deprivation (socioeconomic factors)
- BMI
- Ethnicity
- Other conditions (atrial fibrillation, kidney disease, etc.)
NICE recommends offering statin treatment when QRISK3 is 10% or above — meaning a 10% or greater chance of a cardiovascular event in the next 10 years. Your cholesterol number alone does not determine whether you need treatment — your overall risk profile does.
You can calculate your own QRISK3 at qrisk.org (though interpretation requires clinical context).
The diet question — what actually works
Since diet accounts for 20–25% of blood cholesterol, targeted dietary changes can make a meaningful but not transformative difference. What the evidence actually supports:
Reduces LDL:
- Reducing saturated fat (red meat, full-fat dairy, palm oil, coconut oil) and replacing with unsaturated fats (olive oil, nuts, oily fish, avocado)
- Increasing soluble fibre (oats, beans, lentils, fruit) — oat beta-glucan specifically has good evidence
- Plant stanols and sterols (in products like Benecol or Flora ProActiv) — reduce LDL by 10–15% with consistent daily use
- Reducing refined carbohydrates (lowers triglycerides)
Does NOT significantly affect LDL in most people:
- Reducing dietary cholesterol (eggs, shellfish) — the liver compensates by producing less. The egg ban of the 1990s was based on weak evidence and has been largely revised.
Statins — separating fact from fear
Statins are among the most studied medications in medical history, with decades of data from millions of patients across multiple large randomised controlled trials. For people with elevated cardiovascular risk, they significantly reduce the risk of heart attack and stroke.
And yet they are among the most refused and discontinued medications I see in practice, driven largely by internet misinformation.
What statins actually do: Inhibit the liver enzyme that produces cholesterol (HMG-CoA reductase), reducing LDL by typically 30–50% depending on the statin and dose.
Common statins in the UK: Atorvastatin (most commonly prescribed), rosuvastatin, simvastatin.
Side effects — the honest picture:
- Muscle aches (myalgia): The most commonly reported side effect — approximately 5–10% of patients in real-world use. Usually mild. Rarely, statins can cause myositis (muscle inflammation) or — very rarely — rhabdomyolysis (serious muscle breakdown). If you develop severe muscle pain, stop the statin and contact your GP.
- Liver effects: Statins mildly raise liver enzymes in a small proportion of patients, usually clinically insignificant. Routine liver monitoring is no longer recommended in NICE guidelines unless symptoms develop.
- Diabetes risk: Statins slightly increase type 2 diabetes risk — approximately 1 extra case per 255 patients treated. This risk is far outweighed by cardiovascular benefit in most patients.
- Memory and cognition: No convincing evidence of harm in large trials despite anecdotal reports.
The nocebo effect (side effects caused by the expectation of side effects after reading about them) is real and has been demonstrated in blinded statin studies. Many people who report muscle aches on statins experience the same aches during blinded placebo phases.
If you are on a statin and experiencing side effects: talk to your doctor. There are multiple statins at multiple doses — switching often resolves the issue.
When medication is definitely appropriate
- Familial hypercholesterolaemia — always requires medication
- QRISK3 above 10%
- Existing cardiovascular disease (secondary prevention) — statins have clear mortality benefit
- Diabetes with additional risk factors
When diet and lifestyle alone may be sufficient:
- Low overall cardiovascular risk despite elevated cholesterol
- Young patients with isolated elevated total cholesterol but favourable LDL:HDL ratio and no other risk factors
Sources: NICE Clinical Guideline CG181 — Cardiovascular Disease: Risk Assessment and Reduction (2014, updated 2023); Collins R et al, The Lancet 2016 (Cholesterol Treatment Trialists); Sacks FM et al, NEJM 2017; British Heart Foundation cholesterol statistics 2024; QRISK3 algorithm documentation.