High-density lipoprotein (HDL

High-density lipoprotein (HDL) is one of the five major groups of lipoproteins,

• which, in order of sizes, largest to smallest, are chylomicrons, VLDL, IDL, LDL, and HDL, which enable lipids like cholesterol and triglycerides to be transported within the water-based bloodstream.
•  In healthy individuals, about thirty percent of blood cholesterol is carried by HDL.^[1]

Blood tests typically report HDL-C level, i.e. the amount of cholesterol contained in HDL particles. It is often contrasted with low-density or LDL cholesterol or LDL-C.

• HDL particles are able to remove cholesterol from within artery atheroma ^] and transport it back to the liver for excretion or re-utilization, which is the main reason why the cholesterol carried within HDL particles (HDL-C) is sometimes called "good cholesterol" (despite the fact that it is exactly the same as the cholesterol in LDL particles).
• Those with higher levels of HDL-C seem to have fewer problems with cardiovascular diseases, while those with low HDL-C cholesterol levels (less than 40 mg/dL or about 1 mmol/L) have increased rates for heart disease.^[2]
•  While higher HDL levels are correlated with cardiovascular health, no incremental increase in HDL has been proven to improve health.
• In other words, while high HDL levels might correlate with better cardiovascular health, specifically increasing one's HDL might not increase cardiovascular health.^[3]
• Additionally, those few individuals producing an abnormal, apparently more efficient, HDL ApoA1 protein variant called ApoA-1 Milano, have low measured HDL-C levels yet very low rates of cardiovascular events even with high blood cholesterol values