What is HDL cholesterol? Levels and significance

HDL stands for high-density lipoprotein, one of the main particles that transport cholesterol through the bloodstream. It is commonly referred to as “good cholesterol” because it helps carry excess cholesterol back to the liver, where it can be processed and removed from the body.

However, HDL is only one part of your cholesterol profile. LDL cholesterol, total cholesterol, VLDL, triglycerides and other cardiovascular risk factors also play an important role. Understanding these values together can provide a clearer picture of your heart and blood vessel health.

Table of Contents

• What is cholesterol?
• What are healthy cholesterol levels?
• What are the causes of high or low HDL levels?
• What are the causes of high LDL levels?
• How can I test my cholesterol levels?
• What are the consequences of an LDL level that is too high?
• Key tips for maintaining healthy cholesterol levels
• Cholesterol and eggs
• Frequently asked questions
• Summary

What is cholesterol?

Cholesterol is a fat-like substance found in every cell of the body and is important for many vital functions. For one, it plays a central role in forming cell membranes. Additionally, cholesterol serves as a fundamental building block in the production of certain hormones that regulate various processes in the body, such as sex hormones (estrogen or testosterone). Cholesterol is also necessary for the production of vitamin D, which is important for bone health and the regulation of calcium levels in the blood (CDC, 2024).

Most cholesterol is produced primarily in the liver, alongside some production in the intestines. The liver produces a substantial amount each day to meet the body’s needs. Cholesterol can also be absorbed through the diet, especially from animal-based products such as meat, eggs, and dairy (Heumann, 2024).

Types of cholesterol

Since cholesterol is not water-soluble, it cannot be transported through the bloodstream on its own. Instead, it is carried by special molecules called lipoproteins (composed of fat [lipid] and protein). These transport vehicles deliver cholesterol to the cells that need it and return excess cholesterol to the liver, where it is further processed or excreted. The main lipoproteins in the body are low-density lipoproteins (LDL) and high-density lipoproteins (HDL), each playing a different role in regulating cholesterol levels (Prof. Dr. Püschel, 2022).

• LDL cholesterol (Low-Density Lipoprotein)
  

LDL cholesterol is often referred to as “bad” cholesterol. LDL transports cholesterol in the blood from the liver to the tissues. However, if too much LDL cholesterol is present in the blood, it can accumulate on the walls of the arteries. These deposits, known as plaques, can narrow and harden the arteries—a condition known as atherosclerosis. This narrowing of the arteries reduces blood flow and can lead to serious health problems such as heart attacks and strokes.

• HDL cholesterol (High-Density Lipoprotein)

HDL cholesterol is known as “good” cholesterol. HDL transports excess cholesterol in the blood back from the tissues to the liver, where it is broken down and eventually eliminated from the body. In this way, HDL helps keep the arteries free of cholesterol buildup and reduces the risk of cardiovascular disease. A higher HDL level in the blood is therefore associated with a lower risk of cardiovascular problems.

Source: CDC, 2024.

While having high HDL levels is generally considered a good thing, very high levels (especially above 2.5 mmol/L or 100 mg/dL) may also be associated with certain health risks (such as increased risk of heart disease); particularly in people with other underlying conditions such as chronic inflammation or hypertension. Always consult with a healthcare provider when interpreting your results.

Source: CDC, n.d.; Mayo Clinic, 2024

What are healthy cholesterol levels?

Here are the normal and abnormal cholesterol ranges for adults, which vary by sex:

Source: Cleveland Clinic, 2025

What are the causes of high or low HDL levels?

A low HDL level can have various causes:

• Metabolic syndrome: A cluster of risk factors for heart disease, including low HDL.

• BMI over 25 (Excess weight or obesity)

• Smoking or tobacco use

• ApoA1 deficiency: A genetic condition where the body lacks enough Apolipoprotein A1, an essential HDL component.

• Tangier disease: A rare genetic disorder that causes very low HDL.

• Certain medications: Beta-blockers, hormones, and some diuretics may temporarily lower HDL, but stopping them without medical advice increases heart disease risk.

• Insulin resistance: when the body’s cells don’t respond well to insulin, making it harder to control blood sugar and often leading to lower HDL cholesterol

• Familial combined hyperlipidemia: a genetic condition that causes abnormal cholesterol levels, with HDL too low and LDL too high

A high HDL level can have various causes:

• Alcohol use disorder

• Hyperthyroidism: a condition where the thyroid gland makes too much thyroid hormone, speeding up the body’s processes

• Primary biliary cholangitis: a long-term liver disease where the small bile ducts inside the liver become damaged, leading to liver problems

• Gene changes: alterations in DNA that can affect how the body works or increase the risk of certain diseases

• Side effects from medications

Source: Cleveland Clinic, 2022

It is important to talk to your doctor about the causes of your HDL level and determine whether treatment is necessary.

What are the causes of high LDL levels?

Several modifiable and non-modifiable factors can contribute to elevated LDL:

• Diet high in saturated and trans fats
• Overweight or obesity
• Tobacco use, including smoking and vaping
• Certain medications
• Medical conditions such as diabetes, chronic kidney disease, or HIV
• Older age
• Menopause
• Genetics/family history of high cholesterol

Source: Cleveland Clinic, 2024 

How can I test my cholesterol levels?

With the Homed-IQ Cholesterol and Lipids Test, you can measure your cholesterol levels from home. The test is conducted through a simple finger prick. A certified laboratory then analyzes your blood sample, and you can view the result within a few days.

How often should I test?

There is no fixed recommendation for the frequency of tests.

• General testing: Every 5 years from age 45.

• High-risk groups: Every 12 months if you have high blood pressure, diabetes, heart disease, stroke, kidney disease, or familial hypercholesterolaemia (a genetic condition causing high cholesterol).
  

• Following significant weight gain or weight loss
• After changing medication
• With an increase in alcohol consumption

Source: Healthdirect Australia, 2025

What are the consequences of an LDL level that is too high?

Key tips for maintaining healthy cholesterol levels

• Dietary changes:
  • Reduce saturated and trans fats: Saturated fats and trans fats increase LDL cholesterol in the blood more than other types of fats. Saturated fats are found in animal products such as meat, eggs, and full-fat dairy products. Trans fats are often found in processed foods and baked goods.
  • Eat cholesterol-lowering foods: Choose foods that help lower cholesterol, such as apples, which contain pectin that helps reduce LDL cholesterol. Also opt for foods rich in unsaturated fats (e.g., nuts, seeds, avocados, and fish), as these can positively affect total and LDL cholesterol levels.
• Regular physical activity:
  At least 30 minutes of moderate physical activity per day (e.g., walking, swimming, cycling) can help increase HDL levels and reduce LDL levels.
• Weight loss:
  Studies show that losing just 5–10% of body weight can significantly reduce triglycerides, total cholesterol, and LDL cholesterol (Brown, J. D., et al., 2016). 
• Medication:
  In some cases, cholesterol-lowering medication may be necessary to keep cholesterol levels under control. Talk to your trusted healthcare provider.
• Quitting smoking:
  Smoking damages blood vessels and lowers HDL levels. Quitting smoking can help maintain a healthy cholesterol level.

Sources: Rehberg, C., 2024.

Cholesterol and eggs

Eggs—particularly the yolk—are known for their high cholesterol content. One egg yolk contains about 200 to 210 milligrams of cholesterol, while the egg white contains virtually none. This accounts for roughly two-thirds of the recommended daily intake of around 300 mg for an average adult (Cleveland Clinic, 2024).

For a long time, eggs were considered a risk factor for elevated cholesterol and heart disease. However, newer studies show that dietary cholesterol does not always directly influence blood cholesterol levels. In most people, cholesterol from foods like eggs does not significantly affect LDL or HDL levels in the blood. This is because the liver adjusts its cholesterol production accordingly. That said, in some individuals, eating cholesterol-rich foods can raise LDL cholesterol—often due to a genetic predisposition to high cholesterol levels (Mayo Clinic, 2024). 

What matters most is how well your body regulates cholesterol and whether the ratio of LDL to HDL remains balanced.

Frequently asked questions

Recommended cholesterol intake

The body produces about 700 to 900 mg of cholesterol per day on its own, which is why caution is advised regarding dietary intake. The German Nutrition Society recommends consuming no more than 300 mg of additional cholesterol per day through food.

Source: Maretzke, F., et al, 2020; Angelo, G., 2015

Dietary sources of cholesterol

Cholesterol is primarily found in animal-based products. Some common sources include:

• Meat and poultry: Especially fatty and processed varieties.
• Dairy products: Particularly whole milk, cheese, and butter.
• Eggs: Especially the yolk contains cholesterol.
• Fish and seafood: Some types also contain cholesterol but are often good sources of omega-3 fatty acids.

Since the body produces cholesterol on its own, these foods should be consumed in moderation. To ensure a balanced diet, foods with cholesterol-lowering properties should also be included. Cholesterol-lowering foods:

• Spinach
• Berries
• Avocado
• Citrus fruits
• Walnuts
• Fish
• Green tea
• Olive oil
• Apple

Source: AOK, 2023

What medical treatments help with high cholesterol levels?

In addition to lifestyle changes, there are also medical treatment options for high cholesterol. These include various types of medications that help lower cholesterol and reduce the risk of cardiovascular disease. The choice of treatment depends on your individual health status and risk profile and should be made in consultation with a doctor.

Are eggs healthy – and how many can you eat?

Eggs are nutrient-rich and provide high-quality protein along with important vitamins such as B12, D, and choline. These nutrients support various bodily functions including cell health, brain development, and bone strength. For most people, eggs can be a valuable part of a balanced diet (University of Rochester, 2025; Harvard Health, 2022).

What should I watch out for?

Whether eggs are healthy for you depends on your individual health status. Certain people should be particularly cautious:

• People with a genetic predisposition to high cholesterol (hypercholesterolemia) or existing cardiovascular disease should limit egg consumption and regularly monitor their cholesterol levels.
• People with high blood pressure (hypertension) should be mindful of their total fat intake, as excessive cholesterol consumption can affect vascular health in the long term.

Does how you cook eggs affect cholesterol levels?

The cooking method does not change the cholesterol content of an egg, since nearly all of it is in the yolk. However, how eggs are prepared can indirectly influence your cholesterol levels. Boiled or poached eggs are healthier because they require no added fats. On the other hand, eggs prepared with butter or fatty sides like bacon or sausage increase the intake of saturated fats, which can raise LDL cholesterol. To enjoy eggs healthily, opt for low-fat cooking methods and pair them with nutrient-dense foods like vegetables or whole grains (West, 2023).

How many eggs are safe to eat?

The recommended amount varies depending on lifestyle and health status. For healthy individuals, consuming up to one egg per day is generally considered safe, especially when combined with nutrient-rich foods. For those with risk factors such as high cholesterol or cardiovascular disease, a general guideline is up to 4–5 eggs per week. To be safe, consult with a doctor or consider eating just the egg whites, which are nearly cholesterol-free and still an excellent source of protein (American Heart Association, 2019). 

Summary