What is Low-Density Lipoprotein (LDL) Cholesterol?
Key Takeaways
Cholesterol is a necessary substance for human health, but having high levels in the blood can damage arteries and increase the risk of heart disease.
Heart disease is the leading cause of death in Singapore.
Cholesterol is carried in the blood on lipoproteins. The two primary types of lipoproteins are known as HDL and LDL.
LDL, also known as “bad cholesterol,” serves to carry cholesterol to the body’s tissues. High LDL levels cause excess cholesterol to accumulate in the blood, where it can cause damage.
LDL levels can be checked with a blood test.
If LDL levels are borderline or high, lifestyle changes like decreasing saturated and trans fats, increasing exercise, losing excess body weight, and quitting smoking can help to reduce LDL.
There are also medications that can help to lower LDL, which are used in some cases.
Understanding LDL
Cholesterol is a necessary substance in the human body. Cells throughout your entire body use it to build their outer membranes, and it’s also needed to create many other important molecules, including certain hormones, vitamin D, and bile acids (used for digesting fats). Without cholesterol, your body could not function properly.
At the same time, too much cholesterol can be damaging to your health. When cholesterol levels in the bloodstream are too high, it can deposit into the walls of the arteries. This thickens and narrows the arteries, leading to a condition known as atherosclerosis (sometimes called “hardening of the arteries”).
People with atherosclerosis are at a significantly higher risk for having a heart attack or stroke, which are caused by blockage of an artery to the heart or brain. They may also experience symptoms like chest pain and difficulty exercising, which can create challenges in their daily lives.
Like in many other developed countries, heart disease and atherosclerosis are unfortunately very common here in Singapore. In fact, heart disease accounts for more than one-third of all deaths in our country. The proportion of deaths in younger people (those aged less than 70 years) that are caused by heart disease is actually higher here than in many other parts of the world, including Europe and the United States.
Because it’s a fatty substance, cholesterol doesn’t dissolve well in the blood, which is made up mostly of water. In order to transport cholesterol to your cells, your body creates “packages” known as lipoproteins. Cholesterol and other fats are carried inside of lipoproteins.
There are several different types of lipoproteins found in the bloodstream. The main types are known as low-density lipoproteins (LDL) and high-density lipoproteins (HDL). Cholesterol is carried in both types of lipoproteins. However, the effects of each type are quite different. While HDL cholesterol actually has a protective effect, LDL cholesterol is much more dangerous, and high levels are associated with an increased risk for conditions like heart attacks and strokes.
Why is LDL Called “Bad Cholesterol”?
As mentioned earlier, cholesterol is a necessary substance in the human body, not a harmful one. However, when the levels of cholesterol in the blood are too high, then it may cause harm by depositing into the walls of arteries throughout the body.
The function of low-density lipoproteins, or LDL, is to carry cholesterol out to the tissues of the body, where it can be used to build cell membranes or to make substances like hormones. When LDL levels are high, excess cholesterol remains in the bloodstream, and can potentially become deposited into the walls of the arteries, creating serious health risks. Because of this, LDL is sometimes known as “bad cholesterol.”
There is a strong link between high LDL levels and serious cardiovascular diseases, like heart attacks and strokes. In fact, LDL cholesterol levels are generally recognized as the main measurement of heart disease risk.
By contrast, high-density lipoproteins, or HDL, function to carry excess cholesterol from the tissues back to the liver, where it can be processed for elimination. Higher levels of HDL are generally associated with a lower risk for heart disease.
Factors Influencing LDL Levels
Many different factors can influence your levels of LDL, including:
Genetics. There is a genetic influence on LDL levels. If you have multiple family members with high LDL levels, you’re more likely to have high levels yourself.
Diet. People who eat more saturated fat (found in red meat, butter, and dairy products) and trans fat (found in fried foods and packaged foods) have higher LDL levels. Some studies have also shown that eating more foods that contain cholesterol (such as egg yolks) can also raise your LDL levels, although this association has not been consistent in research. By contrast, those who eat more unsaturated fats (found in plant-based oils) and fiber (found in whole grains, fruits, and vegetables) have been shown to have lower LDL levels.
Body weight. People who have a body weight that’s classified as overweight or obese tend to have higher LDL levels. The body produces more LDL particles, and the particles that it produces tend to be smaller and denser, which makes them more likely to become deposited into the walls of arteries. In addition, having a high body weight increases chronic inflammation throughout the body, which further increases LDL levels.
Physical activity. People who are physically inactive generally have higher LDL levels than those who get more exercise. This is because exercise promotes the clearance of excess cholesterol by the liver.
Smoking. Cigarette smoke contains compounds that prevent the body from clearing LDL from the blood, which leads to higher levels. In addition, certain compounds in cigarette smoke make LDL particles stickier, so they’re more likely to adhere to the walls of arteries, causing blockage. Research has consistently shown an association between smoking and higher LDL levels.
Testing and Understanding LDL Levels
High LDL generally causes no obvious symptoms. The only way to know what your LDL levels are is to have a blood test. This test must be ordered by a physician.
LDL is typically measured as part of a lipid panel. This test measures your LDL, HDL, and triglyceride levels. The test is performed in a fasting state, meaning that you should not have eaten within about 8 to 12 hours before the test. (This is usually accomplished by taking the blood sample in the morning.)
Testing methods vary slightly from one laboratory to the next, so there can be slight differences in what is considered to be a normal result. However, these are the guidelines published by the Ministry of Health:
Desirable: less than 3.4 mmol/L
Borderline: 3.4 to 4.0 mmol/L
High: 4.1 to 4.8 mmol/L
Very high: 4.9 mmol/L or greater
While your LDL level itself has a significant influence on your risk of a heart attack, it’s important to consider it in context. For example, the ratio between LDL and HDL cholesterol is a very important indicator of risk. This ratio will be calculated as part of your lipid panel test. The ratio of LDL to HDL should be 3.5 or less.
Other factors also influence your heart disease risk. For example, people with diabetes or hypertension (high blood pressure) are at an increased risk. Your doctor will interpret the results of your test and help you understand your overall risk, as well as what you can do to reduce it.
Understanding More
How to Lower LDL Levels
If your LDL levels are elevated, then taking steps to lower your LDL can significantly reduce your risk of having a heart attack or stroke. There are several different ways to lower LDL levels. Lifestyle changes are often tried first, including:
Eat a healthy diet. Reducing saturated fats, trans fats, and processed sugars in your diet can help to lower your LDL. Research has shown that the Mediterranean diet helps to lower LDL cholesterol significantly. This diet focuses on eating fish, lean meats (like chicken), nuts, whole grains, vegetables, and fruits, and uses plant-based oils (like olive oil) instead of butter.
Get regular physical activity. Studies have consistently shown that exercise helps to lower LDL. Combining exercise with a healthy diet has been shown to reduce LDL by up to 20%. Any amount of physical activity is helpful, but it’s recommended to get about 20 to 30 minutes of exercise every day. Studies have also found that high-intensity exercise is more effective at reducing LDL. Aim for two to three sessions per week of exercise that challenges you – meaning that you couldn’t hold a conversation while doing it – for 20 to 60 minutes each time.
Maintain a healthy body weight. Having a body weight in the overweight or obese categories is associated with a higher LDL level. Research has shown that, for people who currently have a high body weight, losing 5% of your body weight leads to reductions in LDL levels. Some people are able to accomplish this through lifestyle changes alone, while others benefit from adding GLP-1 RA medications.
Quit smoking. Research has consistently shown a strong association between smoking and high LDL levels. Smoking also increases your risk of heart disease in other ways, such as by causing narrowing of arteries throughout the body. Quitting smoking is one of the most important things you can do to protect your health and reduce your risk of heart disease.
If lifestyle changes don’t bring your LDL into a healthy range, or if you have a high risk of heart disease, then medications may be used to help bring your LDL levels down. Oral medications known as statins are often tried first. There are also other options, such as injectable PCSK9 inhibitors. More than one medication can be used together to help control your LDL levels and reduce your risk of having a heart attack or stroke.
Practical Tips
10 Foods That Can Lower Your LDL (“Bad”) Cholesterol Levels Naturally
Natural Ways to Reduce Cholesterol Levels with Sterol, Beta Glucan, and ALA
LDL and Overall Cardiovascular Health
Your LDL level is only one component of your overall cardiovascular health. It’s important to consider your LDL level in context. This includes comparing it with your HDL level, which is included as part of a standard lipid panel.
There are also many other useful tests that aren’t always included as part of standard screening blood work. For example, your level of C-reactive protein (CRP), a measure of chronic inflammation in your body, has a significant influence on your heart attack risk as well as your risk of other serious conditions.
Apolipoprotein B, as the main protein component of LDL, is an important factor to understanding your overall health. A full panel of tests allows your healthcare provider to assess your cardiovascular and metabolic health.
Establishing a baseline early allows you to track changes over time, so you can make informed decisions about your health.
NOVI Assessment Max provides a holistic cholesterol check that goes beyond the standard test. It offers a comprehensive evaluation of metabolic and hormonal markers, giving you a complete picture of your heart health, and empowering you to take control of it.
Unlike other tests that leave you to interpret results on your own, NOVI Assessment Max includes a doctor consultation, where your results are explained in detail. The doctor then prioritizes areas of improvement and provides actionable recommendations.
Plus, we offer health programs and expert coaches to support you in implementing these recommendations. Whether you need dietary changes, exercise plans, or medical interventions, our experts will guide you every step of the way.