High cholesterol is estimated to cause around 2.6 million deaths per year globally. Learn more about the symptoms and causes of high cholesterol, and how you can keep your cholesterol levels in check through diet and medication in our handy guide on hyperlipidemia.
What is cholesterol?
Cholesterol is a type of fat found in our body which is essential for healthy cell development. Most people get around 20% of their cholesterol from their diet and make about 80% of it in the liver.
When someone has high cholesterol (also known as hypercholesterolemia or hyperlipidemia), it means that there is too much cholesterol in their body. This can be a problem.
Having high cholesterol may lead to a build-up of fatty deposits, known as plaque, inside the blood vessels. This can limit the blood supply to certain parts of our body and cause problems with our organs. Our heart and brain are particularly susceptible to severe damage caused by the narrowing of the blood vessels.
8.3% of people aged 18 to 69 in Singapore have high cholesterol, contributing to an increasing number of people dying every day from cardiovascular disease. Cardiovascular diseases, including heart disease and stroke, are the leading cause of death around the world.
What is the difference between HDL and LDL cholesterol?
There are two forms of cholesterol that we generally talk about in relation to health. These are High-Density Lipid or HDL cholesterol, and Low-Density Lipid, or LDL cholesterol.
Cholesterol is a lipoprotein – lipo meaning that it contains lipids, or fats. The ratio of protein to fat is different within the different types of cholesterol. Cholesterol with a higher protein to fat ratio is higher density than that with a lower protein to fat ratio, giving rise to the distinction between LDL and HDL cholesterol.
While LDL cholesterol is sometimes described as ‘bad’ cholesterol, we actually do need a certain amount in our bodies. However, too much LDL cholesterol can cause problems. When someone’s LDL cholesterol levels are too high, the fats in our blood can begin to lay down small fatty areas known as plaques which narrow the blood vessels and restrict crucial oxygen delivery around the body.
HDL cholesterol is sometimes known as ‘good’ cholesterol. HDL cholesterol removes excess LDL cholesterol from the bloodstream and returns it to the liver, where it is flushed out of the body.
Describing cholesterol as ‘good’ and ‘bad’ is a little over-simplified – we need a bit of both, but it’s essential to get the ratio right.
What cholesterol level is considered high?
Cholesterol levels are determined by taking a blood test, called a lipid profile, which measures the levels of various types of fats in the blood. The blood test for cholesterol describes results in one of two different ways: it may be measured in milligrams of cholesterol per decilitre of blood (mg/dL) or in millimoles per litre (mmol/L).
Blood tests for cholesterol measure the amounts of HDL and LDL cholesterol as well as overall total cholesterol.
The ideal cholesterol levels can be slightly different for people at high risk of cardiovascular disease. When there are other risk factors involved, it’s important to keep an even stricter eye on total cholesterol and cholesterol ratios.
Discuss with your doctor on how often you should get your cholesterol checked. This will depend on your other risk factors for cardiovascular disease and lipid disorders. People with risk factors like a family history of high cholesterol and cardiovascular disease may be advised to start having their cholesterol checked regularly fairly early in life compared to people without increased risk of cardiovascular disease. Your doctor should also be able to tell you what your ideal cholesterol goal should be, taking into account all your individual risk factors.
Signs and Symptoms of High Cholesterol
The fatty plaques of cholesterol in the blood vessels tend to build up slowly over time. Therefore, people with high cholesterol do not usually experience any symptoms until it causes a serious problem, like angina, a heart attack or a stroke. Often, the first symptoms of these conditions will require urgent medical attention.
Symptoms of acute coronary syndromes (such as heart attack or unstable angina) include chest pain or heaviness, sudden shortness of breath, and ‘palpitations’ or an awareness of your heart beat. Stroke symptoms include sudden slurred speech, weakness down one side of the body or a droop on one side of the face. All of these symptoms will require immediate action and emergency hospital treatment.
As high cholesterol can cause acute problems with no warning signs, it’s important to get your cholesterol levels checked by a blood test as part of a routine checkup, as soon and as often as your doctor recommends it. Regular general health screenings test for a range of potential conditions and predisposing factors, helping us make informed decisions about our health and lifestyles, enable effective treatment, and reduce any future risks and complications.
The Risks of High Cholesterol
As cholesterol deposits in the blood vessels build up over time, arteries may narrow and lead to diseases relating to the cardiovascular system. This narrowing of our arteries due to fatty deposits is known as atherosclerosis.
Arteries are blood vessels that take oxygenated blood from the heart to the rest of the body and play an important role in ensuring all parts of our body get the oxygen and nutrients they need to function normally. If an artery becomes narrowed or blocked, parts of our body which receives oxygen and nutrients from that vessel can become damaged as well.
Ischaemic heart disease – heart disease caused by reduced flow of oxygen and nutrients to the heart muscle – is particularly closely linked to high cholesterol.
Cholesterol deposits build up over time, and the plaques can be stable for a long time before causing problems. However, due to the wobbly, fatty nature of the deposits, small pieces may sometimes shear off, triggering the body’s natural clotting process. This can create immediate, life-threatening blockages in the arteries and cause an ischaemic event such as a heart attack or a stroke, causing permanent damage to the affected area.
What causes high cholesterol?
Some people are more likely to have high cholesterol than others. We have control over some of the causes of high cholesterol in our bodies, but not others. Some of the key causes of high cholesterol are:
Our cholesterol level is likely to get higher as we age due to a decline in our body’s function in clearing cholesterol from our blood.
High LDL and low HDL cholesterol levels tend to be more common in men than women, but the differences reduce after the menopause.
Family History of High Cholesterol
Some people have a genetic predisposition to high cholesterol – it runs in the family. This condition is known as familial hypercholesterolaemia and is harder to manage as it occurs even in people with healthy lifestyles. If you or someone in your family is diagnosed with familial hypercholesterolaemia, inform your loved ones so that they are aware of their risk and are able to seek early treatment and prevent the development of serious illnesses and potential complications.
Cholesterol is only found in animal tissues, so people who eat a lot of meat and dairy products ingest relatively more cholesterol, than those with low intake of animal products, and someone on a strictly plant-based or vegan diet will not get any cholesterol at all from their diet. Most of the cholesterol in our bodies is made in our livers rather than obtained from our diet, however, so although plant-based diets are associated with lower cholesterol, it is not a guarantee of low cholesterol.
Obesity or being overweight is not just an indicator of a high fat, unhealthy diet and a lifestyle that’s low in exercise, but also an independent risk factor of high cholesterol. Being overweight makes us more likely to have high cholesterol even if we follow a healthy diet and active lifestyle. It also increases our risk of developing other diseases such as type 2 diabetes, high blood pressure, joint pain and breathing problems.
A substance called acrolein which we inhale when we smoke a cigarette actually inhibits HDL cholesterol’s ability to retrieve harmful LDL cholesterol and return it to the liver for processing.
Pre-Existing Health Conditions
Certain pre-existing health conditions can affect our cholesterol levels. For example, type 2 diabetes lowers our HDL cholesterol and raises our LDL cholesterol. Which may raise our risk of heart disease. Xanthelasma, a condition caused by a buildup of cholesterol deposits under the skin around the eyelids, is also often linked to high cholesterol. High cholesterol may also be worsened by liver or kidney disease.
Some medications, such as oral contraceptives, can increase cholesterol, so people on certain medication regimes may be advised to have their cholesterol levels checked regularly.
How to Reduce High Cholesterol
There are some positive actions we can take independently to improve our cholesterol level and risk of developing cardiovascular disease. As our cholesterol levels can only be measured by blood tests, keeping appointments and consultations with our family doctors is an important part of staying healthy. Some people will also need to take medication for high cholesterol – alongside, not instead of, a healthy diet and lifestyle.
The healthy lifestyle changes we make to improve our cholesterol levels are all good general health advice, and there are no surprises; following a healthy lifestyle makes us healthier. Some of the best ways to improve our cholesterol levels include:
Simply getting a little more exercise can improve cholesterol levels, as well as many other aspects of our health and wellbeing. It is recommended that adults get at least 150 minutes of moderate intensity exercise, or 75 minutes of high intensity exercise every week, in sessions of at least ten minutes each.
Exercise also increases the amount of HDL circulating in the blood, which can help in clearing out the excess ‘bad’ LDL cholesterol. Exercise is good but has a particularly positive effect on cholesterol levels when combined with a healthy diet.
High Cholesterol Food: What to Eat & What to Avoid
Certain foods have been proven to reduce our cholesterol levels. Food products rich in plant sterols and stanols can block our body from absorbing the cholesterol, while others containing polyunsaturated fat can directly lower LDL cholesterol. If you are looking to lower your cholesterol levels, you should include more of these foods in your diet:
- Fruit and vegetables, for vitamins, antioxidants, plant-based oils and fibre.
- High-fibre foods such as brown rice and wholemeal bread.
- Nuts and seeds for heart-healthy oils and fatty acids.
- Beans and other legumes, which are especially high in soluble fibre which directly lowers blood cholesterol levels.
- Oily fish, a great source of omega 3 fatty acids and healthy unsaturated fats.
- Oats, which contain substances called ‘beta-glucans’ which improve digestion, insulin regulation, and have significantly beneficial effects on cholesterol levels.
- Green tea also contains a substance which seems to specifically reduce levels of LDL cholesterol.
On the other hand, there are foods that can raise our cholesterol levels as well. Consuming less of the following food may improve our cholesterol levels:
- Meat and meat-based products like sausages and burgers
- Foods containing palm oil or coconut oil
- Dairy products and foods containing dairy products
Research into the effects of specific foods and dietary supplements is always ongoing, as the field of cardiovascular medicine is an ever-evolving discipline at the forefront of medical research and development.
We know that too much fat in our diet enables our body to make too much cholesterol, and we also directly eat cholesterol when we eat animal-based foods. It’s not enough to just reduce the amount of fat we eat; we also need to consider the type of fats we eat.
Types of Fat in our Diet
There are four broad types of fats in our diet:
- Saturated fats: These are the fats found in animal products like meat and dairy foods. Certain vegetable oils also contain saturated fats, particularly coconut oil, palm oil, and cocoa butter. In general, saturated fat is solid at room temperature. A high intake of saturated fats will increase our cholesterol levels.
- Trans fats: These tend to be the fats found in highly processed foods like margarine. Trans fats act like saturated fats in our bodies and increase cholesterol levels.
- Monounsaturated fats: Found in olive oil and the oils of some nuts and seeds, monounsaturated fats contribute to lower LDL (‘bad’) cholesterol and higher HDL (‘good’) cholesterol.
- Polyunsaturated fats: These are ‘good’ fats found in oily vegetable foods like seeds and nuts. Polyunsaturated fats include omega 3 fatty acids which are good for brain development, healthy skin and joints as well as reducing cholesterol. Omega 3 fats are found in oily fish and some seeds.
The types of fat we eat make a direct difference to our health and cholesterol levels, but if you have too much fat in your diet, it’s not enough to simply swap it for healthier fats. If you eat too much butter and make a healthier choice to switch it to, for example, olive oil, your cholesterol levels may improve but your waistline won’t.
There are foods available which are specifically marketed as reducing cholesterol, including some margarine and yoghurts. These work by including some of the plant-based compounds known to improve cholesterol levels; the plant sterols. Buying these kinds of products isn’t thought to be necessary if you’re following a healthy balanced diet, but can be helpful as a direct replacement for more similar products which don’t include plant sterols.
It’s also important to consider the way you cook your food; don’t forget the fats used in frying and roasting. Switch to healthier fats, or low-fat or fat-free cooking methods wherever possible.
High Cholesterol Medication
There are some effective medications designed to lower cholesterol levels:
The medications that currently have the best evidence for good cholesterol reduction and long-term protection from cardiovascular disease are a group of medications known collectively as ‘statins’. The names of each of these medications end in ‘-statin’.
Some statins, such as simvastatin, work best when taken in the evening. They have a relatively short duration of action, so the time when they’re most active needs to coincide with the time when our bodies create the most cholesterol: when we’re sleeping. Other statins, such as atorvastatin, have a longer duration of action so it doesn’t matter what time of the day they’re taken.
Most people take statins without any significant side effects, but statins are occasionally linked to muscle pains which can be severe enough to mean that that person can’t take them. If you’ve been prescribed statins but find that you develop side effects that you can’t tolerate, it’s important to see a doctor as there may be an alternative which can help to protect you from cardiovascular disease without the same side effects.
Ezetimibe is a medication given as a tablet and reduces the amount of cholesterol that can pass from the gut into the bloodstream. It is not usually as effective as statins so ezetimibe tends to be the second line of treatment for people who cannot tolerate statins. It is, however, still highly beneficial for people at risk from high cholesterol and cardiovascular disease.
Cholestyramine, while less commonly used, can also help to reduce the levels of cholesterol in the blood.
Other medical treatments for high blood cholesterol levels include newer injectable medicines and even a procedure called LDL-apheresis, which is similar to dialysis. In LDL-apheresis, the blood is passed through a machine, the cholesterol is filtered out, and the blood is returned to the body.
Living with High Cholesterol
The long-term risks of untreated high cholesterol are well understood and the steps we can take to try and improve our outcomes are also well evidenced. It’s not always easy to make significant lifestyle changes but the rewards of getting healthier are well worth the work; a healthy lifestyle will mean more energy, feeling generally better in mind and body, and will significantly reduce your risk of serious, even deadly diseases.
If you’re struggling to make or maintain positive, healthy changes in your life, you’re not alone. Help is at hand. GPs, dietitians, and health promotion programmes are available. If you find it difficult to attend routine medical appointments, house call services are available, enabling you to get advice and make healthy choices without delay or difficulty.
However difficult it is to switch to a healthier lifestyle, it’s easier than living with the after-effects of a heart attack or a stroke. The sooner you can make positive changes, the better.
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