Cholesterol Explained: Some Bits Your GP Didn't Have Time to Tell You

You've just had your cholesterol tested. Your GP spent approximately seven minutes explaining the results, handed you a leaflet that looks like it was designed in 1987, and suggested you "try to eat better." You're now sitting at home staring at a piece of paper covered in numbers and acronyms, wondering if you should panic, celebrate, or just have a biscuit.

Welcome. You're in the right place.

Cholesterol is one of those topics that everyone mentions but nobody properly explains. It's simultaneously described as essential for life and a potential harbinger of cardiovascular doom. Your body makes it, your food contains it, and your arteries apparently have strong opinions about it.

Let's sort this out, shall we? No medical jargon without translation. No guilt trips about what you ate last Tuesday. Just the information your GP would have given you if they'd had more than seven minutes and weren't already running forty minutes behind schedule.

What Cholesterol Actually Is (And Why You Have It)

Here's something they don't always mention: cholesterol isn't some toxic substance that's accidentally infiltrated your bloodstream. Your liver is actively making it right now, on purpose, because you need it.

Cholesterol is a waxy, fat-like substance that's essential for building cell membranes, producing hormones (including testosterone, oestrogen, and cortisol), synthesizing vitamin D, and creating bile acids that help you digest food. Without cholesterol, you'd be in rather serious trouble.

The problem isn't that cholesterol exists. The problem is when you have too much of certain types floating around in your bloodstream, particularly when it starts accumulating in places it shouldn't, like the walls of your arteries.

Think of it like this: water is essential for life, but too much water in the wrong place (say, your basement) becomes a significant problem. Cholesterol operates on similar principles.

Where It Comes From

Your body produces about 80% of the cholesterol in your bloodstream. Your liver is the primary manufacturer, churning out roughly 1,000 milligrams daily. The remaining 20% comes from your diet, though this percentage varies considerably based on what you eat and how your body processes dietary cholesterol.

Interestingly, your liver is quite clever about this. When you eat more cholesterol, it typically reduces production. When you eat less, it ramps up manufacturing. It's trying to maintain balance, though this compensation mechanism doesn't work perfectly for everyone, which is partly why some people develop high cholesterol despite eating reasonably well.

The Cast of Characters: LDL, HDL, and Triglycerides

This is where things get slightly more complicated, but bear with me. Cholesterol can't dissolve in blood (being waxy and all), so it travels around your body in little packages called lipoproteins. Think of them as tiny buses transporting cholesterol to various destinations.

There are several types of these buses, but three matter most for your health:

LDL Cholesterol (Low-Density Lipoprotein)

Often called "bad" cholesterol, though this is somewhat unfair. LDL's job is to transport cholesterol from your liver to cells throughout your body. It's doing exactly what it's supposed to do.

The problem arises when there's too much LDL cholesterol circulating. Excess LDL can penetrate artery walls, where it oxidizes (think of it rusting, essentially) and triggers an inflammatory response. Over time, this contributes to atherosclerosis, the buildup of fatty deposits called plaques that narrow arteries and restrict blood flow.

Research consistently shows that elevated LDL cholesterol significantly increases cardiovascular disease risk. A meta-analysis of over 170,000 participants found that each 1 mmol/L reduction in LDL cholesterol was associated with a 22% reduction in major cardiovascular events.

What the numbers mean:

• Below 3 mmol/L: Ideal for most people
• 3 to 4.9 mmol/L: Slightly elevated (your GP will likely discuss lifestyle changes)
• 5 mmol/L and above: High (definitely needs addressing)

HDL Cholesterol (High-Density Lipoprotein)

The so-called "good" cholesterol, and in this case, the nickname is rather apt. HDL works like a cleanup crew, collecting excess cholesterol from your arteries and tissues and transporting it back to your liver for disposal or recycling.

Higher HDL levels are associated with lower cardiovascular risk. HDL appears to have several protective mechanisms: it removes cholesterol from arterial plaques, has anti-inflammatory properties, and may help prevent LDL oxidation.

Long-term cardiovascular research has found that for every 0.025 mmol/L increase in HDL, cardiovascular disease risk decreased by 2 to 3%.

What the numbers mean:

• Above 1 mmol/L (men) or 1.2 mmol/L (women): Good
• Above 1.5 mmol/L: Excellent
• Below 1 mmol/L: Concerning (increases cardiovascular risk)

Triglycerides (The Often-Overlooked Third Party)

Triglycerides aren't technically cholesterol, but they're measured in the same blood test because they're equally important for cardiovascular health. They're a type of fat your body uses for energy.

After you eat, your body converts calories it doesn't immediately need into triglycerides, which are stored in fat cells. Between meals, hormones trigger the release of triglycerides for energy.

High triglyceride levels often indicate you're consuming more calories than you're burning, particularly from refined carbohydrates, sugars, and alcohol. Elevated triglycerides are associated with increased heart disease risk and are often a marker of metabolic syndrome, a cluster of conditions that increase cardiovascular risk.

What the numbers mean:

• Below 1.7 mmol/L: Normal
• 1.7 to 2.2 mmol/L: Borderline high
• 2.3 to 5.6 mmol/L: High
• Above 5.6 mmol/L: Very high (significant health concern)

Understanding Your Test Results (Decoding the Numbers)

Your cholesterol test results will typically show several measurements. Here's what you're looking at:

Total Cholesterol

This is the sum of your LDL, HDL, and 20% of your triglycerides. While useful as a general indicator, it doesn't tell the whole story. You could have high total cholesterol but excellent HDL levels, which changes the risk picture considerably.

UK guidelines:

• Below 5 mmol/L: Desirable
• 5 to 6.4 mmol/L: Borderline high
• 6.5 mmol/L and above: High

The Ratio That Matters

Many clinicians pay particular attention to your total cholesterol to HDL ratio (calculated by dividing total cholesterol by HDL). This ratio provides insight into your cardiovascular risk profile.

For example, if your total cholesterol is 6 mmol/L and your HDL is 2 mmol/L, your ratio is 3:1, which is excellent. If your total cholesterol is 5 mmol/L but your HDL is only 1 mmol/L, your ratio is 5:1, which is less favorable despite your lower total cholesterol.

Optimal ratios:

• Below 4:1: Excellent
• 4 to 6:1: Average risk
• Above 6:1: Elevated risk

Non-HDL Cholesterol (The Number Your GP Might Mention)

This is calculated by subtracting HDL from total cholesterol, giving you all the potentially harmful cholesterol in one number. UK health guidance now recommends using non-HDL cholesterol as a primary target for treatment.

Non-HDL should ideally be below 4 mmol/L for most people, though targets vary based on individual cardiovascular risk factors.

Why Cholesterol Affects Heart Health (The Artery Story)

The connection between cholesterol and heart disease is well-established, though the mechanism is more nuanced than "cholesterol blocks arteries like fat blocks a drain."

Atherosclerosis, the process underlying most heart attacks and strokes, begins when LDL cholesterol particles penetrate the inner lining of artery walls. This is more likely to happen when:

• There's a lot of LDL cholesterol circulating
• The artery lining is damaged (by high blood pressure, smoking, or inflammation)
• The LDL particles are small and dense (more prone to causing problems)

Once inside the artery wall, LDL particles oxidize and trigger an inflammatory response. Your immune system sends white blood cells to deal with what it perceives as a problem, but these cells can become trapped, accumulating cholesterol and forming foam cells. Over time, this creates a plaque, a fatty deposit that narrows the artery.

The real danger occurs when plaques become unstable and rupture. This triggers blood clot formation, which can suddenly block blood flow to the heart (causing a heart attack) or brain (causing a stroke).

Research demonstrates this connection clearly. Analysis of data from over 170,000 participants found that lowering LDL cholesterol by 1 mmol/L reduced the risk of major cardiovascular events by approximately 22% over five years, regardless of how LDL was lowered.

What Actually Affects Your Cholesterol Levels

Your cholesterol levels result from a complex interplay of factors, some within your control and some decidedly not.

Things You Can't Change

Genetics: Your genes significantly influence how your body produces and processes cholesterol. Some people inherit genetic variations that cause their livers to produce excess cholesterol or remove LDL from the blood less efficiently. Familial hypercholesterolaemia, a genetic condition affecting about 1 in 250 people in the UK, causes severely elevated cholesterol from birth.

Age: Cholesterol levels tend to increase with age. This is partly due to decreased liver efficiency at removing LDL cholesterol and partly due to accumulated lifestyle factors over decades.

Sex: Before menopause, women typically have lower total and LDL cholesterol than men of the same age, likely due to oestrogen's protective effects. After menopause, women's cholesterol levels often rise and can exceed men's levels.

Things You Can Influence

Diet: What you eat affects cholesterol levels, though perhaps not exactly as you'd expect. Dietary cholesterol (from eggs, shellfish, etc.) has less impact on blood cholesterol than once thought for most people. What matters more is the type of fat you consume.

Saturated fats (found in red meat, butter, cheese, and processed foods) can raise LDL cholesterol. Comprehensive analysis of randomized controlled trials found that replacing 5% of calories from saturated fats with polyunsaturated fats reduced cardiovascular events by 10%.

Trans fats (in some processed foods) are particularly problematic, raising LDL while lowering HDL. Fortunately, these have been largely eliminated from UK food products.

On the positive side, certain foods actively help lower cholesterol. Soluble fibre (from oats, beans, and fruits) binds cholesterol in the digestive system and removes it before it enters the bloodstream. The GB NHC Register confirms that consuming 3g of beta-glucan from oats or barley daily has been shown to lower blood cholesterol, with the statement: "Beta-glucans contribute to the maintenance of normal blood cholesterol concentrations."

Plant sterols and stanols, compounds naturally present in plants but available in higher concentrations in fortified foods, block cholesterol absorption in the intestines. The GB NHC Register authorizes the claim that plant sterols can lower blood cholesterol, stating: "Plant sterols have been shown to lower/reduce blood cholesterol. Blood cholesterol lowering may reduce the risk of (coronary) heart disease." The authorized amount for this effect is 1.5 to 2.4g of plant sterols per day.

Physical activity: Regular exercise modestly increases HDL cholesterol and can help lower triglycerides. Even moderate activity (brisk walking for 30 minutes most days) makes a difference. Exercise also improves overall cardiovascular health in ways that extend beyond cholesterol numbers.

Weight: Carrying excess weight, particularly around your midsection, tends to increase LDL and triglycerides while lowering HDL. Losing even 5 to 10% of body weight can meaningfully improve your lipid profile.

Smoking: Smoking lowers HDL cholesterol and damages artery walls, making them more susceptible to cholesterol accumulation. Stopping smoking improves HDL levels relatively quickly.

Managing Cholesterol: A Food-First Approach

When your GP tells you that you have high cholesterol, the natural question is: what do I do about it?

The answer depends on your overall cardiovascular risk profile, not just your cholesterol numbers. Your GP will consider your age, blood pressure, smoking status, family history, and whether you have diabetes to assess your cardiovascular disease risk.

For many people, particularly those at moderate risk, lifestyle changes are the first line of approach. This isn't your GP fobbing you off or suggesting you're not worth treating properly. Evidence consistently shows that dietary changes can produce meaningful reductions in cholesterol levels.

What Actually Works

The good news: you don't need to eat exclusively brown rice and steamed vegetables for the rest of your life. The evidence supports a pragmatic, sustainable approach:

Increase soluble fibre: Aim for at least 3g of beta-glucan daily from oats, or 5 to 10g of soluble fibre from various sources. This is one of the most reliable dietary interventions for cholesterol reduction.

Include plant sterols: Consuming 1.5 to 2.4g of plant sterols daily (from fortified foods or supplements) can reduce LDL cholesterol by 7 to 10%. This effect is additive with other dietary changes.

Swap saturated fats for unsaturated fats: Replace butter with olive oil, choose fish over red meat more often, include nuts and seeds. You're not eliminating saturated fat entirely (which would be unnecessarily restrictive), but reducing it makes a measurable difference.

Move regularly: Exercise doesn't dramatically lower LDL, but it improves HDL and overall cardiovascular health. Find movement you actually enjoy and will sustain.

When Medication Becomes Necessary

For people at high cardiovascular risk, or when lifestyle changes alone don't achieve sufficient reduction, medication may be recommended. This isn't a failure of willpower or an indication that dietary changes don't work. It's simply recognizing that some people need additional support to reach target cholesterol levels that substantially reduce their cardiovascular risk.

The decision to start medication is a conversation to have with your GP, considering your individual circumstances, preferences, and risk profile. Lifestyle changes remain important even with medication, and the two approaches work synergistically.

The Realistic Timeline

One question everyone asks: how quickly will my cholesterol improve?

The honest answer is that meaningful changes typically take 6 to 12 weeks of consistent dietary modification. Some interventions work faster than others. Plant sterols, for instance, can begin lowering cholesterol within 2 to 3 weeks. Exercise effects on HDL may take several months to manifest fully.

Your GP will usually suggest retesting after three months if you're making lifestyle changes, or 6 to 12 weeks if you've started medication. This gives enough time to see whether your approach is working without waiting unnecessarily if it isn't.

The key is consistency rather than perfection. Small, sustainable changes maintained over months are far more effective than dramatic temporary overhauls that you'll abandon after three weeks.

The Bottom Line

Cholesterol management isn't about achieving perfect numbers through miserable dietary restriction. It's about understanding your cardiovascular risk and making informed choices that meaningfully reduce that risk while allowing you to actually enjoy your life.

Your cholesterol levels are one piece of information about your health, important but not the entire picture. Work with your GP to understand your complete cardiovascular risk profile and develop an approach that's both effective and sustainable for you.

And if you're feeling overwhelmed by all these numbers and recommendations, remember: your GP had seven minutes to explain this. You've just taken considerably longer to understand it properly. That's already progress.