Cholesterol is a fatty, waxy substance found naturally in the blood. Cholesterol is also known as a lipid. Lipids are essential in maintaining good health and normal bodily functions. However, when the levels of cholesterol in the blood become too high, it can have a negative effect on our health. If cholesterol levels in the blood are too high then it can stick and build up in the artery walls. This build up can start to restrict the blood flow through the arteries, potentially starving the heart, brain and rest of the body of blood supply and hence, oxygen. This restriction can lead to heart disease, such as a heart attack or stroke.
Cholesterol is transported around the body by proteins in your blood. Combined they are called lipoproteins. The two main types of lipoproteins are known as:
- Low-density lipoprotein (LDL) - LDL is sometimes referred to as ‘bad cholesterol’. This is because the LDL carries cholesterol away from the liver, delivering it to the cells that require it. If there’s an excess amount for the cells to use then the remaining cholesterol begins to build up in the artery walls, leading to disease of the arteries.
- High-density lipoprotein (HDL) - HDL is also known as ‘good cholesterol’. This is because HDL carries cholesterol away from the cells and back to the liver. After being taken to the liver it will either be broken down or removed from the body as a waste product.
High cholesterol (which actually refers to high levels of LDL) can be caused by a number of factors. These include:
- Eating an unhealthy diet: Dietary cholesterol can be found foods like eggs and prawns. They can be eaten moderation with very little influence on the blood cholesterol levels and can be eaten in moderation. However, foods that are rich in saturated fat contain higher levels of LDL and should be avoided or consumed very occasionally.
- Being physically inactive or over weight: This can increase the levels of LDL or ‘bad cholesterol’ in the blood.
- Smoking: There is a chemical found in cigarettes called acrolein. This chemical stops the HDL from delivering the fatty deposits back to the liver, which will lead to a build up of cholesterol and narrowing of the arteries (atherosclerosis).
- Drinking too much alcohol: This can increase your cholesterol levels as well as your triglyceride (other fatty substances) levels.
- Family history of heart disease: having a close relative with a history of coronary heart disease or stroke can carry an increased chance of having high cholesterol.
- Family history of high cholesterol: Having a close relative who also suffers from hypercholesterolaemia (high cholesterol) can increase your increase the likelihood of having the condition.
- Having diabetes or high blood pressure: often people with these conditions present with higher levels of cholesterol.
- Medical conditions such as kidney and liver disease can cause raised levels of cholesterol. An under active thyroid gland has also been associated with higher levels of cholesterol.
- Ethnicity: Certain ethnic groups carry an increased risk of having higher blood cholesterol. These groups are Indian, Pakistani, Bangladeshi and Sri Lankan.
- Age: With increased age comes an increased risk of having higher levels of blood cholesterol.