Cardiovascular disease refers to all diseases of the heart (cardio) and blood vessels (vascular). The blood vessels affected are the arteries which carry oxygen rich blood to the cells.
What is cholesterol?
Cholesterol is a fatty substance that the body needs to make hormones, vitamin D and bile acids to aid digestion. Cholesterol is also needed to build and maintain the outer wall of cells. Your body makes some cholesterol (mainly in the liver) and some comes from the food you eat. Put simply, cholesterol is essential for life.
Triglycerides are another type of fat found in your blood. Again, your body makes some triglycerides and some comes from the food you eat. Triglycerides are used for energy and any excess is stored as fat. High levels of triglycerides are associated with increased risk of cardiovascular disease.
How is cholesterol moved around the body?
Cholesterol is a fatty substance which cannot dissolve in blood (like oil and water), so it is carried around by proteins. These fat (lipo) and protein complexes are called lipoproteins.
There are two main types:
LDL (Low Density Lipoprotein) is the ‘bad’ cholesterol – increases the risk of cardiovascular disease
LDL transports cholesterol to the cells. The body’s cells take up the LDL cholesterol via an LDL receptor (this is the process which is faulty in FH). This controls the amount of cholesterol in the blood. The protein component of LDL is called apolipoprotein B (Apo B).
HDL (High Density Lipoprotein) is the ‘good’ cholesterol – helps to protect against cardiovascular disease
HDL transports cholesterol from the cells to the liver for removal. HDL can also act as an antioxidant. The major protein component of HDL is called apolipoprotein A1 (Apo A1).
If there is too much LDL cholesterol in the blood, it can deposit in the walls of the arteries giving rise to cardiovascular disease.
These deposits are known as plaque or atheroma (pronounced ath-er-O-ma) and the process is called atherosclerosis (pronounced ath-er-O-skler-O-sis).
As shown in Figure a below, over time the plaque causes the arteries to narrow and eventually become blocked. This causes a lack of oxygen to the part of the organ supplied by the artery and will result in tissue damage, see Figure b below. Plaques can also rupture, forming a blood clot, which rapidly blocks the artery.
Depending on where the cardiovascular disease is located and how severe it is it can cause:
- angina or heart attacks if it occurs in the heart (known as heart disease, coronary heart disease (CHD) or coronary artery disease (CAD)), see Figure b above
- strokes if it occurs in the brain
- other circulation problems (peripheral artery disease) if it occurs in other parts of the body e.g. leg pain when walking (intermittent claudication) and erectile dysfunction in men.
The higher your LDL cholesterol, the greater your risk of getting cardiovascular disease.
Risk factors are factors which increase the likelihood of getting a disease.
You are more likely to get cardiovascular disease if you:
- have high LDL cholesterol (‘bad’ cholesterol) or have been diagnosed with FH
- have low levels of HDL cholesterol (‘good’ cholesterol)
- have high levels of triglycerides
- have diabetes
- have high blood pressure
- are overweight or obese
- eat a poor diet (diet high in saturated and trans fats)
- do little physical activity
- consume excess alcohol
- suffer from depression
These are modifiable risk factors (can be changed by lifestyle and/or medication).
Other factors are:
- age (cholesterol increases with age)
- gender (females are somewhat protected from cardiovascular disease by their female hormones prior to menopause but after menopause tend to catch up with men)
These are non-modifiable risk factors (cannot be changed by lifestyle or medication).
The more risk factors you have the greater your risk of getting cardiovascular disease.
Causes of high cholesterol
A survey completed in 2011/13 found one in three Australian adults had high total cholesterol. This equates to 5.6 million Australians. This makes high cholesterol a major health concern in Australia.
Poor lifestyle choices such as a poor diet, lack of physical activity, obesity and smoking all increase the risk of high cholesterol and cardiovascular disease.
Cholesterol increases with age and as Australia has an aging population this is adding significantly to the rise in cholesterol levels.
High cholesterol can also be caused by a genetic condition called Familial Hypercholesterolaemia (FH), which is unrelated to lifestyle or increasing age.
There are also other medical causes for high cholesterol, but your doctor will check for these.
The advice in this website does not replace advice from your GP or healthcare provider.