What is LDL Cholesterol?
Imagine your bloodstream is like a busy motorway, and fat (lipids) needs to travel to different parts of the body. But fat and water don’t mix well—just like oil and water. So, your body packages fat into little “cars” called lipoproteins, which help transport cholesterol and fat around the body.
LDL (Low-Density Lipoprotein) is one type of these “cars.” It carries cholesterol from the liver to the rest of the body. However, if too much LDL is floating around, it can stick to blood vessel walls, leading to plaques that cause heart disease. That’s why LDL cholesterol is often called “bad cholesterol.”
On a blood test, LDL cholesterol is an estimate of the amount of cholesterol carried by LDL particles, but it does not measure the number of LDL particles themselves—just the cholesterol they contain.
What is ApoB, and How Is It Different?
Now, let’s look at Apolipoprotein B (ApoB). If LDL particles are like cars, then ApoB is like the steering wheel—it’s a protein attached to LDL that helps it function and enter cells.
But here’s the key difference:
Each LDL particle has exactly one ApoB protein. So, if you measure ApoB, you’re directly counting the number of LDL particles, not just how much cholesterol they carry.
This is important because some people have many small LDL particles, while others have fewer but larger ones. Even if two people have the same LDL cholesterol level, the person with more LDL particles (more ApoB) is at higher risk for heart disease.
✅ LDL cholesterol = Measures cholesterol content inside LDL, but not the number of particles.
✅ ApoB = Counts LDL particles directly (better risk marker than LDL cholesterol).
✅ Fasting triglycerides = Measures fat in the blood after fasting (linked to metabolic health).
✅ ApoE = A protein that helps remove certain fat-carrying particles and influences genetic risk for heart disease and Alzheimer’s.
Difference between dietary cholesterol and the good and bad cholesterol
Dietary cholesterol comes from eggs, meats and dairy
packaged into chylomicrons for transport after eating
Endogenous cholesterol is made by the liver and cells, producing around 75% of total cholesterol - transported around in VLDL, LDL and JDL particles
The body needs cholesterol to build cell mabarnes, hormones, vitamin D and bile acids for digestion. Most of your cholesterol is made by you own body, not from food
Homeostasis:
if you eat more cholesterol, your liver makes less to keep levels stable
if you eat less cholesterol, your liver makes more to compensate
What has a greater impact on cholsterol?
Saturated fats and trans fats by reducing the liver;sability to remove LDL from the blood