Cholesterol is found in every cell of the body and has important natural functions. It is manufactured by the body but can also be taken in from food. It is waxy and fat-like in appearance.
Cholesterol is oil-based and so does not mix with the blood, which is water-based. It is therefore carried around the body in the blood by lipoproteins.
The parcels of cholesterol are carried by two types of lipoprotein:
- Low-density lipoprotein (LDL – cholesterol carried by this type is known as ‘bad’ cholesterol)
- High-density lipoprotein (HDL – cholesterol carried by this type is known as ‘good’ cholesterol).
Cholesterol has four main functions, without which we could not live. It:
- Contributes to the structure of cell walls
- Makes up digestive bile acids in the intestine
- Allows the body to produce vitamin D
- Enables the body to make certain hormones.
Causes of high cholesterol
High cholesterol is a major risk factor for coronary heart disease, a cause of heart attacks, and reducing blood lipid levels lowers the cardiovascular risk.
High levels of LDL lead to a build-up of cholesterol in the arteries, whereas HDL carries cholesterol to the liver for removal from the body. A build-up of cholesterol is part of the process that narrows arteries, called atherosclerosis, in which plaques form and cause restriction of blood flow.
High cholesterol levels are a result of modifiable and non-modifiable risk factors. Two major risk factors, diet and exercise, are highly modifiable, meaning that something can be done to change these risk factors and reduce the likelihood of having high cholesterol.
Limiting intake of fat in the diet helps manage cholesterol levels. In particular, it is helpful to limit foods that contain:
Meat, cheese and egg yolks are sources of cholesterol.
- Cholesterol (from animal foods, such as egg yolks, meat and cheese)
- Saturated fat (found in some meats, dairy products, chocolate, baked goods, and deep-fried and processed foods)
- Trans fat (found in some fried and processed foods).
Being overweight or obese can also lead to higher blood LDL levels, with regular exercise helpful in managing this risk factor.
The primary causes of high cholesterol are genetic – very high LDL levels are found in the inherited condition familial hypercholesterolemia.
Abnormal cholesterol levels may also be secondary to the following:
- Diabetes
- Liver or kidney disease
- Polycystic ovary syndrome
- Pregnancy and other conditions that increase levels of female hormones
- Underactive thyroid gland.
- Drugs that increase LDL cholesterol and decrease HDL cholesterol (progestins, anabolic steroids and corticosteroids).
Symptoms of high cholesterol
Having high cholesterol levels, while a risk factor for other conditions, does not itself present any signs or symptoms. Unless routinely screened through regular blood testing, high cholesterol levels will go unnoticed and could present a silent threat of heart attack or stroke.
Treatment and prevention of high cholesterol
- Eat a ‘heart-healthy diet’ (for example, use low-fat toppings and sauces, and avoid foods high in saturated fat; eat vegetables, fruits and fiber-rich whole grains)
- Take regular exercise
- Avoid smoking
- Achieve and maintain a healthy weight.
- Lipid-lowering therapy
