High-density lipoproteins (HDL) are one of the five major groups of lipoproteins responsible for transporting lipids throughout the body. HDL particles are composed of approximately 80-100 proteins per particle, organized by one, two or three apolipoprotein A (ApoA) molecules. As HDL particles circulate in the blood, they enlarge by aggregating more fat molecules, transporting up to hundreds of fat molecules per particle.

Functions of HDL

The primary function of HDL is to remove excess cholesterol from cells, including those within arterial walls, and transport it back to the liver for excretion or re-utilization. This process is known as reverse cholesterol transport. HDL also has anti-inflammatory and antioxidant properties, helping to prevent or even regress atherosclerosis.

Structure and Composition

HDL particles are typically composed of 80–100 proteins per particle, organized by one, two or three ApoA molecules. The lipids carried by HDL include cholesterol, phospholipids, and triglycerides, with variable amounts of each.