What is blood cholesterol?

Cholesterol is a waxy, fat-like substance necessary to make hormones and vitamin D, and to help you digest food. Your body produces cholesterol, and it’s also in some foods.

The human body uses cholesterol to build cells, but too much can put you at risk of heart disease. 

Types of cholesterol

The two most common types of cholesterol are:

Low-density lipoprotein (LDL) – the ‘bad’ cholesterol
High-density lipoprotein (HDL) – the ‘good’ cholesterol.

Low-density lipoprotein

Low-density lipoprotein makes up most cholesterol and is bad because it can stick to the walls of arteries and cause a fatty build-up called plaque. Too much plaque leads to blockages that prevent blood from flowing properly to the heart.

High-density lipoprotein

High-density lipoprotein is healthy because it carries LDL away from the arteries and back to the liver to be broken down and then passed as waste.

Cholesterol and triglycerides

Triglycerides are the most common fat in the body. Being overweight, eating a lot of high fat and sugary foods, or drinking too much alcohol can increase your triglyceride levels.

High triglycerides, along with either increased LDL cholesterol or decreased HDL cholesterol can increase your chances of developing fatty build-ups in the arteries – and a higher risk of heart attack and stroke. 

What are the signs and symptoms of high cholesterol?

High cholesterol generally doesn’t have obvious symptoms, but it can increase the risk of serious health conditions if left untreated. That’s why it’s important to get a blood test and regular check-ups.

If you are 45 or older (30 or older, if you are Aboriginal or Torres Strait Islander), see your doctor for a cholesterol test as part of a Heart Health Check. If you have a family history of high cholesterol, speak to your GP about your heart disease risk.

Why is high cholesterol bad for you?

If you have high cholesterol, you can develop fatty deposits in your blood vessels. This makes it difficult for blood to flow through the arteries. If these deposits break apart, they can form a clot that leads to a heart attack or stroke.

Total cholesterol is a measure that includes good and bad cholesterol. It’s not always the best measure of your risk of heart disease on its own. The best way to understand these levels and your risk for heart disease is to see your GP for a Heart Health Check.

What causes high cholesterol?

There is no single cause of high cholesterol, but there are some controllable risk factors (e.g. smoking) and non-controllable risk factors (e.g. age).

Risk factors for high cholesterol include:

Age
Smoking
Lack of physical activity
Overweight or obesity
Family history
Unhealthy diet.

No matter what the cause, improving your lifestyle, including your diet, can help reduce your risk of heart disease.

How is cholesterol measured?

Cholesterol is measured with a blood test called a lipid panel or lipid profile. A cholesterol test usually involves having your blood drawn from a vein in your arm. The test can help determine your risk of atherosclerosis, which is a build-up of plaque that narrows or blocks arteries.

How to interpret your cholesterol results

Guidelines for target cholesterol levels vary based on factors such as age and family history, so ask your doctor what levels are right for you.

A full blood-cholesterol test usually checks:

Total cholesterol
LDL cholesterol
HDL cholesterol
Triglycerides
Non-HDL cholesterol.

How can you lower high cholesterol?

There are several ways to help lower high cholesterol, like staying active and eating or avoiding certain foods.