Causes of high cholesterol 

Many different factors can contribute to high blood cholesterol, including lifestyle factors such as smoking, an unhealthy diet and lack of exercise, as well as having an underlying condition, such as high blood pressure or diabetes.

Lifestyle

Your lifestyle can increase your risk of developing high blood cholesterol. This includes:

  • An unhealthy diet – some foods, such as liver, kidneys and eggs, contain cholesterol ("dietary cholesterol"), but this has little effect on blood cholesterol. It's the total amount of saturated fat in your diet that's more important to watch. Read more about preventing high cholesterol
  • Lack of exercise or physical activity – this can increase your level of "bad cholesterol" (low-density lipoprotein, or LDL). 
  • Obesity – if you're overweight, it's likely that you'll have higher levels of LDL cholesterol and triglycerides, and a lower level of high-density lipoprotein (HDL).
  • Drinking excessive amounts of alcohol – regularly drinking large amounts of alcohol can increase your cholesterol and triglyceride levels.
  • Smoking – a chemical in cigarettes called acrolein stops "good cholesterol" (HDL) transporting cholesterol from fatty deposits to the liver, leading to narrowing of the arteries (atherosclerosis).

Underlying conditions

People with high blood pressure (hypertension) and diabetes often have high cholesterol. Some other health conditions that can also cause raised levels of cholesterol include:

Treating the underlying condition can help to reduce cholesterol. 

Other factors

There are a number of factors associated with high cholesterol that can't be changed and which increase your risk of having a heart attack or stroke. Doctors refer to these as "fixed factors". They include:

  • family history of early coronary heart disease (CHD) or stroke – you're more likely to have high cholesterol if you have a close male relative (father or brother) aged under 55, or a female relative (mother or sister) aged under 65, who's had CHD or stroke
  • a family history of a cholesterol-related condition  for example, having a parent, brother or sister with familial hypercholesterolaemia (see below)
  • age  the older you are, the greater the likelihood of your arteries narrowing (atherosclerosis)
  • ethnic group  people of Indian, Pakistani, Bangladeshi and Sri Lankan descent are at increased risk of having a heart attack
  • sex – males are more likely to have heart attacks than females

If you have a fixed risk factor, or several fixed risk factors, it's even more important to look at your lifestyle and any underlying conditions you may have.

Familial hypercholesterolaemia

Familial hypercholesterolaemia is the medical term for high cholesterol that runs in families. It's caused by a gene alteration that’s inherited from a parent, rather than an unhealthy lifestyle.

People with familial hypercholesterolaemia have raised cholesterol from birth, which can lead to the early development of heart problems, such as atherosclerosis and CHD.

In the UK, familial hypercholesterolaemia is thought to affect about 1 in 500 people, which means that approximately 120,000 people are thought to be affected.

There’s a 1 in 2 (50%) chance that a child or sibling (brother or sister) of someone with familial hypercholesterolaemia will also have the condition.

Read more about the importance of early identification and diagnosis of familial hypercholesterolaemia.




Triglycerides

Triglycerides are another type of fatty substance in the blood. They're produced by the liver and are also found in dairy products, meat and cooking oils.

An increased risk of having a high triglyceride level may be due to:

  • being overweight
  • eating a diet high in fatty or sugary foods
  • drinking a large amount of alcohol
  • genetic factors
  • having diabetes

Page last reviewed: 27/08/2015

Next review due: 27/08/2017