Cholesterol and Heart Risk

What your cholesterol results mean and how they fit into your overall risk of heart attack and stroke

Cholesterol is often reduced to a simple message: lower is better.

The reality is more useful — and more nuanced.

Your body needs cholesterol to build cells and make hormones. The concern is not cholesterol itself, but whether certain cholesterol-containing particles are contributing to fatty plaque inside your arteries.

Your cholesterol result also does not sit alone. Its importance depends on your age, blood pressure, smoking status, diabetes, kidney health, family history and whether you have already had cardiovascular disease.

Understanding that bigger picture helps you focus on the changes most likely to protect your heart and brain.

What is cholesterol?

Cholesterol is a waxy, fat-like substance. Most is produced by your liver, with a smaller amount coming from food.

Because cholesterol cannot travel freely in the bloodstream, it is carried inside particles called lipoproteins.

A standard lipid blood test usually measures:

• Total cholesterol
• LDL cholesterol
• HDL cholesterol
• Triglycerides

These results provide different pieces of information about your cardiovascular health.

LDL cholesterol: the main concern

Low-density lipoprotein, or LDL, is often called “bad cholesterol”.

That description is imperfect, but the principle is important. When there are too many LDL particles circulating in the blood, cholesterol can enter the walls of arteries and contribute to plaque formation.

Over time, this process — called atherosclerosis — can narrow or damage arteries. If a plaque ruptures and a blood clot forms, it may cause a heart attack or stroke.

In general, the more LDL cholesterol is reduced in someone at meaningful cardiovascular risk, the more their risk can be lowered.

However, the LDL result should still be interpreted alongside the rest of the person’s health rather than treated as an isolated pass-or-fail number.

HDL cholesterol: helpful, but not a treatment target by itself

High-density lipoprotein, or HDL, is often called “good cholesterol” because it helps transport excess cholesterol back to the liver.

A lower HDL result can be associated with higher cardiovascular risk. But raising HDL with a medicine or supplement has not generally been shown to provide the same benefit as lowering LDL.

This means your GP will usually focus more on your overall cardiovascular risk and your LDL cholesterol than on trying to increase HDL as a goal by itself.

Regular activity, not smoking and improving metabolic health may support a healthier lipid profile overall.

What are triglycerides?

Triglycerides are another type of fat carried in the blood.

They may rise with:

• Diabetes or insulin resistance
• Excess alcohol
• Overweight or obesity
• Some medicines
• Certain kidney, liver or thyroid conditions
• A diet high in excess energy or refined carbohydrates
• Inherited lipid disorders

Raised triglycerides can contribute to cardiovascular risk. Extremely high levels may also increase the risk of pancreatitis.

Your GP may repeat the test, review possible causes or arrange further investigation depending on how high the result is and whether the blood sample was taken fasting.

Does dietary cholesterol matter?

Foods such as eggs, prawns and organ meats contain cholesterol, but dietary cholesterol is not usually the main driver of high LDL levels for most people.

The type of fat in your overall diet is generally more important.

Saturated and trans fats can raise LDL cholesterol. These are common in foods such as butter, cream, fatty and processed meats, pastries, cakes, deep-fried foods, and products containing coconut or palm oil.

Replacing some saturated fat with unsaturated fats from olive oil, nuts, seeds, avocado and fish can help lower LDL cholesterol. This is more useful than simply removing every food that contains cholesterol.

Why one cholesterol number is not enough

A cholesterol result cannot tell you your entire risk of heart attack or stroke.

For example, an LDL result may carry different implications in:

• A healthy 35-year-old non-smoker
• A 65-year-old with high blood pressure
• Someone with diabetes or chronic kidney disease
• A person who has already had a heart attack
• Someone with a strong family history of early cardiovascular disease

Australian guidance recommends estimating absolute cardiovascular risk by considering several factors together. These include age, blood pressure, cholesterol, smoking, diabetes and relevant medical history.

Someone with apparently modest cholesterol may still have high overall risk. Another person with a mildly raised result may have relatively low short-term risk but still benefit from lifestyle changes and long-term monitoring.

When is cholesterol considered very high?

There is no single cholesterol target that applies to everyone.

The Australian cardiovascular risk guideline identifies total cholesterol above 7.5 mmol/L or LDL cholesterol of 5 mmol/L or higher as severe hyperlipidaemia. These results generally warrant active management even when the calculated overall cardiovascular risk appears low.

Very high results may suggest an inherited condition, particularly when there is:

• High cholesterol from a young age
• A parent, sibling or child with very high cholesterol
• Heart attack or stroke at an unusually young age in the family
• Several affected relatives

Familial hypercholesterolaemia

Familial hypercholesterolaemia, or FH, is an inherited condition that causes high LDL cholesterol from birth.

It affects about 1 in 250 people, but many remain undiagnosed. Without treatment, lifelong exposure to high LDL can substantially increase the risk of premature cardiovascular disease.

Identifying FH matters not only for the individual but also for their family. Parents, siblings and children may need testing.

Lifestyle remains important, but people with FH usually require medication because healthy eating and exercise alone are unlikely to lower LDL sufficiently.

How is cholesterol tested?

A lipid profile is a standard blood test.

Both fasting and non-fasting samples can be suitable. Your GP will tell you whether fasting is needed, especially if triglycerides are high or other blood tests are being performed at the same time.

For many healthy adults, cholesterol testing begins as part of cardiovascular risk assessment from around age 45, or earlier for Aboriginal and Torres Strait Islander people and those with additional risk factors.

Testing may be required sooner or more often if you have:

• Diabetes
• High blood pressure
• Kidney disease
• Known heart or vascular disease
• A strong family history
• Previously abnormal cholesterol
• Treatment for high cholesterol

What can lower LDL cholesterol?

Improve the quality of dietary fats
Replace some saturated fats with unsaturated fats.

Examples include:

• Olive or canola oil instead of butter
• Nuts or seeds instead of pastries or chips
• Fish instead of processed meat
• Avocado or nut butter instead of cream-based spreads

Eat more soluble fibre
Soluble fibre can reduce cholesterol absorption.

Useful sources include:

• Oats
• Barley
• Lentils
• Beans
• Chickpeas
• Psyllium
• Apples
• Pears
• Vegetables

Be physically active
Regular aerobic and resistance exercise supports cardiovascular and metabolic health. It may improve triglycerides and HDL, and can contribute to weight management and blood-pressure control.

Stop smoking
Smoking causes arterial damage and greatly increases cardiovascular risk. Stopping smoking is often more important than making small changes to an individual cholesterol result.

Work towards a healthier weight where relevant
For people living with excess weight, modest weight loss may improve triglycerides, LDL cholesterol, blood pressure and blood glucose.

Plant sterol-enriched foods can lower LDL modestly in some people, although they should complement — not replace — an overall healthy eating pattern.

When are medicines recommended?

Statins are the most commonly used cholesterol-lowering medicines.

They reduce cholesterol production in the liver and lower LDL cholesterol. More importantly, they reduce the risk of heart attack and stroke in people likely to benefit.

Your GP may recommend a statin because:

• Your overall cardiovascular risk is high
• You have already had cardiovascular disease
• Your LDL cholesterol is very high
• You have diabetes, kidney disease or another important risk factor
• Lifestyle changes have not reduced risk enough

A statin may be appropriate even when the cholesterol result does not look dramatically high, because treatment decisions are based on overall risk rather than one number.

Most people tolerate statins well. Speak with your GP if you develop symptoms or concerns rather than stopping treatment yourself. The dose or medicine can often be adjusted, and other cholesterol-lowering treatments are available when needed.

Start with one change

Choose one practical action:

• Ask your GP when your cholesterol was last checked
• Replace butter with an unsaturated spread or olive oil
• Add oats or legumes several times a week
• Reduce processed meats
• Take a regular walk
• Stop smoking with support
• Take prescribed cholesterol medicine consistently

The most useful step depends on your overall cardiovascular risk, not just your laboratory result.

The bottom line

Cholesterol is one important part of cardiovascular risk.

LDL cholesterol can contribute to plaque inside arteries and increase the risk of heart attack and stroke. But the significance of your result depends on your age, blood pressure, smoking, diabetes, kidney health, family history and previous cardiovascular disease.

Healthy eating, physical activity, not smoking and weight management can all help. Medicines provide substantial additional protection for people at higher risk.

Do not focus only on whether your cholesterol is labelled “normal” or “high”. Ask what the result means for your overall heart risk — and what action will make the greatest difference.