Which lipoprotein contains the highest phospholipid content?

• A. HDL
• B. LDL
• C. VLDL
• D. Chylomicrons

Answer: (A)

Phospholipids make up the surface shell of every lipoprotein, forming its amphipathic layer that stabilizes the particle and mediates interactions with enzymes and receptors. Among the lipoproteins, the one that has the highest proportion of phospholipids on its surface is HDL. This particle is small and dense, with a relatively high surface-area-to-core lipid ratio, so its surface is richer in phospholipids (and free cholesterol) relative to its core lipids. In contrast, VLDL and chylomicrons are dominated by triglycerides in their cores, so the lipid fraction is TG-heavy and phospholipids constitute a smaller share. LDL is more cholesterol-ester rich on its surface, with less phospholipid than HDL. Therefore, HDL has the highest phospholipid content.