What is cholesterol?

Cholesterol is a soft, fatty substance in the blood which plays an important role in cell membranes, to manufacturer many hormones and bile for digestion. Most of the cholesterol in the body is manufactured in the liver and then transported by the blood to the rest of the body. Some foods we eat from animal sources contain cholesterol, and this is referred to as dietary cholesterol.

Why are high cholesterol levels dangerous?

Everyone has cholesterol in their blood but too much cholesterol increases the risk of having a heart attack or a stroke. High blood cholesterol levels can slowly cause build-up of cholesterol and other waste products in the inner walls of arteries. If left unchecked, it can eventually form plaques; thick hard deposits that can narrow arteries and make them less flexible. This process is called atherosclerosis. If a clot forms and blocks a narrowed artery that feeds the heart or brain, it can result in a heart attack or stroke. High cholesterol is one of the most important risk factors for cardiovascular disease.

‘Good’ and ‘bad’ cholesterol

Cholesterol that is transported from the liver to the rest of the body is carried in transporters called low density lipoproteins, commonly known as LDL. A different transporter, called high density lipoprotein or HDL, collects cholesterol from the rest of the body and the blood vessels, and returns it to the liver. Because high levels of LDL cholesterol are associated with heart disease, it is often called ‘bad cholesterol’. HDL ‘cleans’ the blood vessels of cholesterol and is therefore commonly referred to as ‘good’ cholesterol.

Blood cholesterol tests often also include a triglyceride test. This is a measure of the amount of fat that is being transported in the blood, which could be from fatty food that was recently eaten, or from fat production in the liver. High fasting levels of triglycerides in the blood increases the risk of heart diseases and strokes.

Most people with high cholesterol feel perfectly healthy, there are usually no warning signs, which is why it is sometimes called a “silent killer”. The only way to find out is to have a blood test. For an accurate result, fast from food and liquids for at least nine hours before the test. If a total cholesterol level is high, it is important to know what type of cholesterol is high.

What should my cholesterol reading be? For most healthy people normal cholesterol levels are:
  • Total cholesterol of LESS than 5 mmol/L
  • LDL cholesterol level of LESS than 3 mmol/L
  • HDL cholesterol levels of MORE than 1.2 mmol/L for women or 1.0 mmol/L for men
  • Fasting triglyceride levels of LESS than 1.7 mmol/L
People who are at a higher than normal risk for cardiovascular events may have stricter individual targets as advised by their doctor or specialist. This includes people who have:
  • Existing heart disease, previous strokes or heart attacks, peripheral vascular disease
  • Diabetes, kidney disease and other medical conditions that increase the risk of heart disease
  • Familial hypercholesterolaemia (inherited high cholesterol)
How often should cholesterol be tested?

All adults should have a fasting lipogram at least once in young adulthood (from age of 20). If cholesterol levels are normal, the test should be repeated again in a few years. People with diabetes, kidney disease or who are overweight should have their cholesterol levels monitored frequently by their doctor.

If ‘bad’ cholesterol levels are high or someone is at a high risk of heart disease, cholesterol levels should be checked every six months. Children don't need to have their levels tested unless they have a family history.

There are various physical and lifestyle factors that can increase the likelihood of developing high blood cholesterol. Being aware of risk factors will help to identify the changes necessary to lower risk. Some of these risk factors include:

  • Eating too much saturated fat.
  • Medial conditions such as an underactive thyroid gland or chronic kidney failure.
  • Family history: If a parent of grandparent had high cholesterol, this trait can be inherited. Some people have naturally very high blood cholesterol levels, due to a rare hereditary condition called familial hypercholesterolaemia (FH). If one family member is diagnosed with FH, it is vitally important that all members of the family have a full fasting lipogram done to test if they also have FH.
  • Physical inactivity
  • Being overweight or obese, especially around the middle. Being overweight increases the chances of abnormal cholesterol levels. People with type two diabetes or metabolic syndrome often have low HDL cholesterol levels and elevated triglyceride levels.
  • Drinking too much alcohol.
  • Smoking and tobacco use.

How can cholesterol levels be lowered?

Depending on the individual’s risk profile, a doctor may recommend medication or first making lifestyle changes. Whether someone is started on medication or not, diet, physical activity and lifestyle changes are critical.

Changes to the eating habits and other lifestyle factors can help to improve abnormal cholesterol levels. Read more about how this can improve the different types of blood cholesterol levels below:

The most common medication to treat high cholesterol levels is a group of medications called statins. These medications reduce the amount of cholesterol produced in the liver, effectively reducing total and LDL cholesterol levels. Other medications include fibrates, ezetimibe, and several others. A doctor will decide whether someone should start cholesterol medication, and which type and dosage they need. As with most medications, a small percentage of people may experience side effects. If side effects occur, medication should not be stopped, but rather alternatives should be discussed with a doctor.

Cholesterol medication should be taken regularly to work, and may need to be taken indefinitely. Importantly, starting cholesterol medical should be done together with lifestyle changes, not instead of them!

  • Choose healthier fats: Cut down on unhealthy sources of fats high in saturated and trans fats which can raise cholesterol levels. These can be found in foods such as fatty and processed meats, chicken skin, butter, ghee, cream and hard cheeses, coconut or palm oil, pies, pastries, biscuits, crackers, fast foods and deep-fried potato or slap chips. Replace these with healthier fats rich in mono- and polyunsaturated fats such as plant oils, peanut butter, nuts and seeds, avocado and fish.
  • Eat high fibre foods. Soluble fibre especially helps to lower cholesterol levels and can be found in foods such as oats, lentils, beans, vegetables and fruit. Increase daily dietary fibre intake by choosing high fibre whole-grain options, eating at least 5 fruit and vegetables daily and including a wide variety of legumes such as beans, peas, lentils and soya.
  • Weight loss. Even as little as 2-5 kg weight loss already starts to improve raised blood cholesterol levels.
  • Eat food high in dietary cholesterol in moderation. Certain foods, notably eggs, organ meats, shellfish and red meat in general contain cholesterol. However, dietary cholesterol in food does not typically make a great contribution to blood cholesterol. It is more important to eat foods low in saturated and trans fats. Most people that eat a generally healthy diet can consume roughly 7 eggs a week and do not need to avoid occasionally eating high-cholesterol foods like shellfish or liver. In cases where cholesterol levels are very high or uncontrolled, a doctor or dietitian may suggest limiting these foods.
  • Add plant sterols or stanols. When used as part of a healthy diet, plant sterols or stanols can help to lower cholesterol levels by up to 10-15% by reducing the absorption of cholesterol in the small intestine. This could be provided by sterol-enriched foods such as Flora pro-activ.
  • Weight loss. Even as little as 2-5 kg weight loss already starts to improve raised blood cholesterol levels.
  • Reduce total carbohydrate intake, especially refined carbohydrates like white bread, white rice, pastries, biscuits, etc. and replace these with sources of mono- and polyunsaturated fats such as avocado, olive oil, nuts and seeds. Choose carbohydrate foods that are lower in glycaemic index and higher in fibre.
  • Only consume alcohol in moderation if at all
  • Limit added sugars such as sweets, chocolates, sweetened soft drinks, fruit juices, flavoured water and sweetened dairy products.
  • Weight loss. Even as little as 2-5 kg weight loss already starts to improve raised blood cholesterol levels.
  • Reduce alcohol intake.
  • Reduce total carbohydrate intake, especially refined carbohydrates like white bread, white rice, pastries, biscuits, etc.
  • Limit added sugars such as sweets, chocolates, sweetened soft drinks, fruit juices, flavoured water and sweetened dairy products.
  • Choose foods high in omega 3 fats, especially naturally oily fish such as sardines, pilchards, mackerel and salmon, which should be eaten at least twice a week. Plants products such as walnuts, flaxseed, canola are also good sources. If this is not possible, a medical professional may recommend omega 3 supplements.
  • Reduce intake of saturated fat and replace this with sources of mono- and polyunsaturated fats such as avocado, olive oil, nuts and seeds.
  • Get active. Be physically active for at least 150 minutes a week e.g. 30 minutes five times a week, by doing moderate- to vigorous-intensity aerobic physical activity. This helps to increase ‘good’ HDL cholesterol levels and reduce high triglyceride levels
  • Be smoke-free. Quit smoking and avoid secondhand smoke. This will help in particular for low HDL levels.

For more advice, contact The Heart and Stroke Foundation South Africa on 021 422 1586 or email heart@heartfoundation.co.za.

  Content was last reviewed in November 2017. Dietary advice for the management of cholesterol is based on the 2016 European Society of Cardiology and European Atherosclerosis Society Guidelines for the Management of Dyslipidaemias