The effects of niacin on lipoprotein subclass distribution.

Dyslipidemia is a heterogeneous metabolic condition; high-density lipoprotein (HDL), low-density lipoprotein (LDL), and very-low-density lipoprotein represent families of lipoprotein particles that differ in size and composition and vary in atherogenicity. Lipoprotein subclasses containing apolipoprotein B promote atherosclerosis, of which the most atherogenic appear to be the small, dense LDL and large very-low-density lipoprotein subclasses, while the large HDL2 subclass, which transports esterified cholesterol from the periphery to the liver, is considered the more cardioprotective. Niacin has long been known to improve concentrations of all major lipids and lipoproteins, but it also has consistently favorable effects on subclass distribution. A MEDLINE search was conducted for clinical studies reporting the effects of niacin on lipoprotein subclasses. The niacin-associated elevations in HDL cholesterol likely stem from differential drug effects on subclasses, producing favorable changes in levels of HDL2 and apolipoprotein A-I. Niacin has more moderate LDL cholesterol-lowering efficacy, but this change is associated with an increase in LDL particle size and a shift from small LDL to the less atherogenic, large LDL subclasses. In addition, it also tends to decrease concentrations of the larger very-low-density lipoprotein subclasses. Niacin confers diverse benefits with respect to both the quantity and quality of lipid and lipoprotein particles.