Cholesterol facts you likely haven’t heard of (Part 1)
You have likely been told that ‘bad’ LDL cholesterol clogs your arteries. The ‘story’ goes something like this. LDL cholesterol circulates in your blood and can get ‘stuck’ in your heart arteries causing plaques. These can build up till they block the artery causing coronary artery disease including heart attacks. The higher the LDL, the more cholesterol gets stuck in your arteries causing blockages and heart attacks.
Stories often have an element of truth, and this is no difference. There is no doubt that LDL cholesterol plays a part in the development of heart disease. However, the process of causing plaques is complex. The first step to understanding the development of plaques is identify the real culprits.
The first step is to understand that (supposedly) ‘bad’ LDL is not just one thing. Research has highlighted that not all LDL particles are created equal. In particular, the size and density of LDL particles—specifically, small dense LDL (sdLDL) versus large benign LDL (lbLDL) play distinct roles in cardiac risk. Understanding these differences is crucial for a more accurate assessment of cardiovascular risk and for tailoring prevention strategies.
LDL Particle Subtypes: An Overview
LDL particles transport cholesterol through the bloodstream. They can be classified based on their size and density. Small dense LDL (sdLDL) particles are smaller and heavier, while large benign LDL (lbLDL) particles are larger and less dense. Traditional cholesterol tests panels test for total LDL cholesterol but do not distinguish between these subtypes. Recent advances in laboratory testing allow for the measurement of LDL particle size and concentration, providing deeper insight into cardiovascular risk profiles.
Small Dense LDL: Higher coronary artery risk
SdLDL particles are considered particularly dangerous. Their size and density allow them to penetrate the arterial wall where they are susceptible to oxidation. Oxidised LDL and subsequent inflammation of the artery is the real driver behind plaques formation. I have included more information at end of this article.
Numerous studies have demonstrated a strong association between elevated levels of sdLDL and an increased risk of coronary heart disease, independent of total LDL cholesterol levels.[1] Individuals with proportionately high sdLDL often have other features of metabolic syndrome, such as insulin resistance, elevated triglycerides, and low HDL cholesterol, further compounding their cardiac risk. The good thing is that particle size can be greatly influenced by our diet. More on this next edition.
Large Benign LDL: Lower coronary artery risk
In contrast, large benign LDL particles are less likely to contribute to plaque development. Their large size makes it difficult for them to infiltrate the arterial wall, and they are less prone to oxidation. As a result, higher concentrations of lbLDL particles are not as strongly associated with cardiovascular events as sdLDL. Some studies suggest that individuals with a predominance of llbLDL particles, even if their total LDL cholesterol is elevated, may have a lower risk of developing heart disease compared to those with high levels of sdLDL despite lower total LDL.
Do you have high LDL Cholesterol?
Many people do! However, your cholesterol test tells you nothing on whether your LDL cholesterol is causing plaques. Next edition, we look at how we can change our cholesterol particle size through our diet. Supplements can also help.
Coronary Calcium CT Scan
I have high cholesterol. Because LDL is potentially a risk factor I need to know is whether I am forming plaques. About 5 years ago, I was aware of a heart scan that showings whether plaques are forming in my heart arteries. This widely available test is called a Coronary Calcium CT scan. These are not funded and cost about $500. Read more at https://theheartgroup.co.nz/patient-info/diagnostic-tests/calcium-score-test/.
My Scan showed that despite an LDL of 4, my heart arteries are in very good condition with no evidence of plaques. My doctor had been suggesting statins to me for years because of my high cholesterol. Based on the scan, he said that given my age of 65 (at the time) he would not recommend statins because I was clearly not forming plaques.
Cholesterol particle size test.
You can also have these done in NZ. These are not funded and cost about $500. Read more at Read more at https://theheartgroup.co.nz/patient-info/diagnostic-tests/calcium-score-test/.
Next week we look at actual solutions. Please contact me if you have questions or need advice.
Research on LDL particle size and risk of heart disease
Since 2010, several studies have advanced our understanding of the distinct roles that small dense LDL (sdLDL) and large benign LDL (lbLDL) particles play in cardiovascular disease. A 2012 meta-analysis published in the Journal of the American College of Cardiology confirmed that higher concentrations of sdLDL are independently associated with increased risk of coronary artery disease, even after controlling for total LDL levels. In 2015, a study in Atherosclerosis highlighted that individuals with a predominance of sdLDL exhibited greater arterial stiffness and subclinical atherosclerosis compared to those with mainly lbLDL, regardless of overall cholesterol levels.
Further research in 2017 (European Heart Journal) demonstrated that interventions such as weight loss, exercise, and dietary modification can shift LDL particle distribution from small dense to larger benign forms, thereby reducing cardiovascular risk. In 2020, a cross-sectional analysis in the journal Lipids in Health and Disease showed that patients with metabolic syndrome had significantly higher sdLDL concentrations, which correlated with markers of inflammation and endothelial dysfunction. Collectively, these studies underscore the importance of assessing LDL particle size—rather than relying solely on total LDL cholesterol—for a more nuanced evaluation of cardiac risk and for guiding targeted prevention strategies.
An example of such research can be read at https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0241993
[1] This means that regardless of your total level, it is the amount of sdLDL that is the real risk factor.