If you’ve had advanced cholesterol testing, you might be wondering: Is high LDL-P dangerous? While most standard panels measure LDL cholesterol (LDL-C), newer tests can reveal your LDL particle number, which provides a more detailed look at the actual number of cholesterol-carrying particles in your blood.

Let’s take a closer look at the LDL particle number meaning for heart disease risk, possible causes, and how to optimize your LDL-P and cardiovascular wellness. 

What Is LDL Particle Number (LDL-P)?

Let’s start with what LDL-particle number means. LDL-P isn’t measured on its own; it’s part of an advanced panel that includes the quantities of LDL particles categorized by size. 

In my experience as a cardiovascular dietitian, having a high LDL particle number typically coincides with having high apoB and high LDL.

Here’s another way to look at LDL-P:

They’re like buses carrying cholesterol and triglycerides in your bloodstream. On your blood test, the LDL number is the amount of cholesterol being transported in the LDL buses in your blood. For years, LDL has been called “bad cholesterol” and a marker for atherosclerosis risk. 

However, as scientists learn more, they are now looking at the number and size of the LDL particles (those LDL buses) in the bloodstream and how they are associated with atherosclerosis risk. 

So what if your LDL-P is high? Research indicates that if the LDL number is normal but the LDL particle size is high, the risk of atherosclerosis and heart disease increases. Others may have both high LDL and high LDL-P. 

Discordance, in which the LDL-C and LDL-P numbers don’t match, can happen because of variability in cholesterol being carried within LDL particles. This can result in different risk profiles even with similar LDL-C values. For example, someone with high LDL-C and low LDL-P might have larger, cholesterol-rich particles with somewhat lower atherogenicity, whereas someone with low LDL-C but high LDL-P might have a lot of small, cholesterol-poor particles that have higher atherogenicity. 

LDL-P vs LDL-C vs ApoB: What’s the Difference?

Here’s a quick breakdown of what these three terms mean: 

• LDL‑C (low-density lipoprotein cholesterol) measures the total amount of cholesterol carried by LDL particles, but doesn’t reflect how many particles there are. 
• LDL‑P (LDL particles) indicates the number of LDL particles themselves, which can vary widely in the amount of cholesterol each carries. In some people, LDL may appear normal, but LDL particles are high, and in this case of discordance, we want to target LDL particles.
• ApoB (apolipoprotein B) represents how many atherogenic lipoprotein particles there are, since each contains one ApoB molecule. It may more accurately capture heart disease risk than LDL‑C alone.

Why a High LDL Particle Number Increases Atherosclerosis Risk

Atherosclerosis takes time to develop and goes through 4 stages. Understanding these stages and what a high LDL-P has to do with the process can help protect your heart health and reduce your risk.

Stage 1: Endothelial cell injuries

Endothelial cells line the inside of your blood vessels. In the smallest vessels (capillaries), they form a single-cell layer that allows for the exchange of oxygen, nutrients, and waste between blood and tissues. 

When these cells are injured (from high blood pressure, high blood sugar, elevated LDL or triglycerides, kidney disease, or smoking), it sets the stage for atherosclerosis. Instead of healing with a “scab,” these injuries invite cholesterol to collect at the site, starting the disease process.

Stage 2: Lipoprotein Deposition

After an injury, LDL particles (“buses” carrying cholesterol) infiltrate the damaged area and unload their cholesterol cargo. A higher LDL-P increases the chance that some will be present at injury sites. 

Smaller LDL particles and those with ApoB are especially likely to lodge in the damaged vessel lining. This creates a fatty streak (an early sign of atherosclerosis) and localized inflammation.

Stage 3: Inflammation

Your immune system detects cholesterol buildup and sends immune cells to the site of the injury. These cells begin to address the damage, but also contribute to plaque formation. 

Over time, if more cholesterol and immune cells collect, the fatty streak can grow, narrowing the blood vessels and potentially blocking blood flow. This plaque is made up of cholesterol and immune cells.

Stage 4: Creation of a Fibrous Cap

Once the immune system has the injury under control, a fibrous cap eventually develops to stabilize the inflamed plaque. Like a scab over a wound, it’s made of fibrous tissue that acts as a protective barrier to keep plaque from breaking loose. 

If the cap is thin or unstable, it can rupture and trigger a clot, leading to a heart attack or stroke. Over time, the cap may harden, but the narrowed, stiff blood vessel remains. This hardened plaque is atherosclerosis.

What Causes High LDL Particle Number?

Several factors can make LDL‑P high, including:

Insulin resistance and metabolic syndrome

When your body struggles to regulate blood sugar effectively, this often leads to elevated triglycerides, lower HDL, and an increase in small, dense LDL particles, raising the total number of LDL particles in circulation. Insulin resistance is a core feature of metabolic syndrome, which also includes abdominal obesity, high blood pressure, and abnormal blood lipids, all of which can worsen LDL‑P.

Poor nutrition

Diets that are lack nutrient adequacy and/or are high in processed carbohydrates, sugary beverages, and ultra-processed foods can trigger spikes in blood sugar and insulin. Over time, this can also promote elevated ApoB and inflammation.

Genetics

Some people inherit genetic conditions like familial hypercholesterolemia (FH) that cause their bodies to produce or retain more LDL particles. In these cases, it’s still important to adopt healthy lifestyle habits; without changing your lifestyle, LDL will likely climb even higher.

Hypothyroidism or hormonal imbalances

An underactive thyroid has been associated with reduced HDL and increased LDL particles. Other hormonal shifts, like during menopause, can also negatively influence lipid metabolism and increase heart disease risk.

Chronic inflammation

Ongoing inflammation, whether from autoimmune disease, poor gut health, or chronic stress, can damage endothelial cells and encourage the body to produce more lipoproteins. Inflammation also makes LDL particles more likely to become oxidized, increasing their atherogenic potential.

How to Lower LDL-P Naturally

When it comes to lowering LDL-P and preventing atherosclerosis, a targeted lifestyle approach is essential. That means addressing cholesterol numbers but also optimizing overall blood vessel health by doing things like:

• Optimizing your nutrition. Add more minimally processed, fiber-rich foods, lean protein and healthy fats and reduce refined carbs, added sugars, and saturated fats that can promote insulin resistance and inflammation. 
• Evaluating your habits. Regular exercise, stress management, and adequate rest can help improve insulin sensitivity, reduce inflammation, promote hormonal health, and support a healthier lipid profile. Smoking damages blood vessels and triggers oxidative stress that can contribute to plaque formation. 
• Managing existing conditions. Managing high blood pressure, diabetes, or thyroid imbalances is key to reducing LDL‑P and preserving vascular health.
• Adhering to prescribed medications. Lifestyle changes are always a good idea, but they may not always be enough to move the needle in some individuals, in which case your care team might recommend medications alongside science based nutrition. 

Read the full client story by clicking on the image above.

Who Should Get Their LDL Particle Number Tested?

Information is powerful, so if you’re curious to know more about your heart disease risk, understanding your LDL-P number can be helpful. 

This is especially recommended if you have a family history of heart disease, have been diagnosed with insulin resistance, prediabetes, or metabolic syndrome, or if you have atherosclerosis with a “normal” traditional lipid panel. 

Is Your LDL Particle Number High? Next Steps

I created my 6-week heart optimization group program called Optimize to optimize your blood vessel health and address each stage of the atherosclerosis process using science-based nutrition and lifestyle behavior change recommendations. 

We work together to address atherosclerosis, reduce modifiable heart disease risk factors, and understand how to achieve optimal laboratory parameters like LDL-P. Apply for the next cohort here.

For more heart disease prevention tips to your inbox every Tuesday morning, join my email list here.

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