A New Way of Thinking About Atherosclerosis: LDL and the Artery Wall

Atherosclerosis is the underlying process that leads to many heart attacks and strokes.

For decades, it has often been explained in a very simple way: “bad cholesterol” leaks into damaged blood vessels.

The traditional story suggested that LDL cholesterol only entered the artery wall once the inner lining of the blood vessel, known as the endothelium, was injured. According to this view, damage to the artery allowed LDL particles to penetrate the vessel wall, which then triggered plaque formation.

Recent research is beginning to challenge that explanation.

A growing body of evidence suggests that LDL cholesterol can cross even healthy artery walls, meaning plaque formation may begin earlier and more subtly than previously thought.

Understanding this process helps us rethink what atherosclerosis really is, why it develops, and how cholesterol levels influence long-term cardiovascular risk.

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What Is Atherosclerosis?

Atherosclerosis is a process in which fatty deposits known as plaques build up within the walls of arteries. Over time these plaques can narrow blood vessels, reduce blood flow, and increase the risk of cardiovascular events such as heart attacks and strokes.

In its early stages, atherosclerosis often causes no symptoms. This is why many people can have developing plaque for years before it is detected.

When symptoms do occur, they may include:

• Chest discomfort or pressure
• Shortness of breath with exertion
• Reduced exercise tolerance
• Pain or cramping in the legs when walking

These symptoms of atherosclerosis usually appear only once blood flow becomes significantly restricted.

When plaque develops specifically in the arteries that supply the heart, the condition is known as coronary artery atherosclerosis, one of the main causes of coronary artery disease.

Because early signs of atherosclerosis are often silent, prevention focuses heavily on managing risk factors such as cholesterol levels, blood pressure, metabolic health, and lifestyle habits.

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How LDL Cholesterol Enters the Artery Wall

A 2025 review published in Arteriosclerosis, Thrombosis, and Vascular Biology (2025;45:468–480) highlights an important shift in our understanding of atherosclerosis.

The research shows that LDL cholesterol particles can cross the artery wall even when the blood vessel lining appears healthy. This occurs through an active transport process called transcytosis.

Transcytosis involves small structures called caveolae, along with receptors such as SR-B1 and ALK1, which shuttle LDL particles from the bloodstream into the artery wall.

Once LDL enters the artery wall, it can become trapped and modified. This can trigger inflammation and begin the process of plaque development.

Interestingly, the 2019 ESC/EAS Dyslipidaemia Guidelines already reflect this concept. Their diagrams illustrate LDL particles entering and becoming retained within the artery wall as an early step in the development of atherosclerosis.

This newer understanding suggests that LDL entering the artery wall may not require prior damage to the endothelium. Instead, it may be part of a normal physiological process that becomes harmful when LDL exposure is high over long periods of time.

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Why Cholesterol Exists in the First Place

To understand this process properly, it is important to remember that cholesterol is not inherently harmful. In fact, cholesterol is essential for many biological functions.

Cholesterol plays an important role in:

• Building cell membranes
• Producing hormones
• Supporting immune responses
• Repairing damaged tissues

While cells are capable of producing their own cholesterol, this process requires time and energy. LDL particles provide a convenient delivery system, transporting cholesterol through the bloodstream so that tissues can access it when needed.

From an evolutionary perspective, this system likely provided advantages during periods of growth, infection, injury, or stress, when rapid tissue repair or immune activity was required.

In modern environments, however, chronically elevated LDL cholesterol levels can lead to excessive delivery of cholesterol into the artery wall, increasing the likelihood of plaque formation.

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Why Long-Term Cholesterol Exposure Matters

One important concept in cardiovascular prevention is cumulative exposure to LDL cholesterol over time.

Research shows that cells do not require high levels of circulating LDL to function normally. In fact, some individuals with certain genetic variations naturally maintain very low LDL cholesterol levels throughout life without adverse effects.

Similarly, studies of traditional populations with naturally lower cholesterol diets show that very low LDL cholesterol can be compatible with good health.

What appears to matter most is not a single cholesterol test result, but lifetime exposure to LDL particles.

When cholesterol levels remain elevated for many years, LDL particles are more likely to enter and become retained in the artery wall. Over time, this increases the risk of plaque development and progression of atherosclerosis.

For this reason, long-term management of LDL cholesterol and ApoB levels remains one of the most important strategies for preventing cardiovascular disease.

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Lifestyle Factors That Influence Atherosclerosis

For people interested in lifestyle approaches to cardiovascular health, this broader understanding of atherosclerosis highlights several additional areas that influence vascular health.

While lowering LDL cholesterol remains central, other factors can influence how LDL behaves within the artery wall and how the body responds to it.

These include:

• Reducing chronic inflammation
• Supporting endothelial function
• Improving metabolic flexibility
• Managing stress levels
• Maintaining a nutrient-dense diet

These strategies help create an internal environment where LDL entering the artery wall is less likely to trigger inflammatory plaque formation.

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The Central Role of LDL and ApoB

Despite these additional factors, reducing LDL cholesterol and ApoB remains the most direct way to lower the risk of atherosclerosis.

Lowering LDL reduces the number of particles circulating in the bloodstream and therefore reduces the likelihood that they will enter and become retained within the artery wall.

In other words, controlling LDL levels directly addresses the root cause of plaque formation.

Lifestyle strategies, metabolic health, and vascular support remain valuable, but they work best as complementary approaches alongside managing LDL exposure over time.

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A More Complete View of Atherosclerosis

The emerging understanding of LDL transport across the artery wall suggests that LDL entering the artery wall is a natural biological process rather than purely a sign of damage.

What determines whether this process becomes harmful is:

• The amount of LDL present in circulation
• How long elevated cholesterol levels persist
• How the body manages inflammation and repair

From a prevention perspective, this means addressing both sides of the equation.

Reducing LDL cholesterol and ApoB levels lowers the number of particles available to enter the artery wall. At the same time, supporting metabolic and vascular health can reduce the likelihood that retained LDL will trigger inflammation and plaque formation.

Together, these approaches provide the most evidence-based strategy for reducing long-term cardiovascular risk.

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References

• Arterioscler Thromb Vasc Biol. 2025;45:468–480. DOI: 10.1161/ATVBAHA.124.321549
• 2019 ESC/EAS Guidelines for the management of dyslipidaemias: https://academic.oup.com/eurheartj/article/41/1/111/5556353