LDL
The cholesterol delivery truck - but not the whole story. LDL transports cholesterol to cells that need it, but when oxidized, it can contribute to arterial plaque. Particle size, count, and oxidation status matter more than just the standard LDL-C number.
What LDL Actually Does
Cholesterol Delivery
Transports cholesterol from liver to cells that need it for membranes, hormones, and other functions.
Triglyceride Transport
Also carries some triglycerides and fat-soluble vitamins (A, D, E, K) and antioxidants.
Immune Function
LDL particles can bind and neutralize bacterial toxins. Part of innate immunity.
Cell Signaling
LDL receptors trigger signaling cascades when LDL binds. Involved in cellular regulation.
From VLDL
LDL is created when VLDL particles lose triglycerides. It's the remnant that's cholesterol-rich.
Receptor Clearance
Normally cleared by LDL receptors on liver and cells. Problems start when clearance is impaired.
LDL-C vs LDL-P: What's the Difference?
LDL-C (Standard Test)
- Measures cholesterol content in LDL
- Usually calculated, not directly measured
- Can be normal while particle count is high
- May miss risk in metabolic syndrome
- The standard test most doctors order
LDL-P / ApoB (Advanced)
- Measures number of particles
- Each particle has one ApoB protein
- Better predictor of cardiovascular events
- Especially useful when LDL-C and risk diverge
- More particles = more chances for arterial entry
Small Dense vs Large Buoyant LDL
Small, Dense LDL (Pattern B)
More atherogenic. More particles needed to carry same cholesterol. Penetrates arterial wall more easily. More susceptible to oxidation. Associated with metabolic syndrome.
Large, Buoyant LDL (Pattern A)
Less atherogenic. Fewer particles carry more cholesterol. Less likely to penetrate arterial wall. More resistant to oxidation. Associated with better metabolic health.
High triglycerides + low HDL often indicates small dense LDL, even when LDL-C looks normal.
Oxidized LDL: The Real Villain
Native LDL isn't recognized by macrophages - oxidized LDL is:
What Causes Oxidation
Free radicals, inflammation, high blood sugar, smoking, seed oils, lack of antioxidants.
What Happens
Macrophages engulf oxLDL via scavenger receptors, becoming foam cells that form arterial plaques.
Protection
Antioxidants (C, E, polyphenols), reduce inflammation, control blood sugar, avoid seed oils.
Better Markers Than LDL-C
ApoB
One protein per atherogenic particle. Best single marker of cardiovascular risk according to many researchers.
Triglyceride/HDL Ratio
Ratio <2 is ideal. Predicts particle size and insulin resistance. Easy to calculate from standard panel.
LDL-P (Particle Count)
Direct count of LDL particles. Discordance with LDL-C often reveals hidden risk.
Lp(a)
Genetic risk factor. High Lp(a) increases risk regardless of LDL. Check at least once.