Your family
You are more likely to have high cholesterol if a member of your family has had early heart disease or stroke.
A few people have a particular type of inherited cholesterol problem called familial hypercholesterolemia (FH). This affects about one in 500 people, being passed from generation to generation through a faulty gene. If one of your parents, a brother or sister has FH, you have a 50% chance yourself of having the condition, which can cause high cholesterol from birth onwards. If you're found to have FH, you need to be particularly vigilant about avoiding the other risk factors for high cholesterol and heart disease, as well as taking medication.
If you're a man
Men are more likely than women to have high cholesterol.
Your age
Cholesterol levels tend to rise as you get older.
Your ethnic group
People who have Indian, Pakistani, or Bangladeshi origins are more likely to develop high cholesterol.
Your diet
You are more likely to have high cholesterol if you eat a lot of fatty foods, such as cheese, butter, cream, cakes, biscuits, and sausages. For more information, see the section on Eating well.
Your physical activity
If you have a couch potato lifestyle and don't take much exercise, you're more likely to have higher levels of 'bad' LDL cholesterol. For more information, see the section on Living well.
Your weight
Being on the heavy side can increase your levels of 'bad' LDL, and lower your 'good' HDL cholesterol.
Alcohol
Regularly drinking too much has several drawbacks for your health, including your cholesterol levels.
Cigarettes
Smoking tobacco can lower the levels of 'good' HDL cholesterol in your system, reducing your protection against heart disease.
Certain medications
High cholesterol has been linked to some medications, including oestrogen, testosterone, oral steroids and blood pressure medications (diuretics).
Multiple conditions
High cholesterol tends to come as part of a dangerous package of risks to the heart. This is why people with high cholesterol are more likely to suffer from diabetes and high blood pressure, together with obesity. High cholesterol is twice as common in people with diabetes compared with non-diabetics. Research shows that 48 per cent of men with high blood pressure and 61 per cent of women with high blood pressure also have raised cholesterol.
So managing high cholesterol is even more important if you have these other health problems, or indeed if you already have heart disease. Similarly, if you've had a heart attack or stroke, you should start cholesterol-lowering medication.
Some other medical conditions that are also linked to raised cholesterol are kidney and liver disease and an underactive thyroid (hypothyroidism).
Find out more about diabetes.
Find out more about high blood pressure.
Can I reduce my risk?
Some risk factors for high cholesterol can't be changed. For instance, there's nothing you can do about your family or your age!
But if you do have these fixed risks, then it's even more important to combat the risks you can influence - namely, your lifestyle.
For some people, healthy lifestyle changes are all that are needed to lower cholesterol to the levels recommended by doctors. Others will need to take medication to reduce high cholesterol as well as making lifestyle changes.
By taking these steps, almost everyone can achieve healthy cholesterol levels.