Abstract and Niacin Overview

Niacin has long been used as an effective lipid-altering therapy, particularly for raising HDL-C and lowering triglyceride levels. In addition, niacin modestly lowers LDL-C levels. LDL-C circulates in the blood as a heterogeneous population of various sized particles, with smaller LDL particles widely considered to be more closely associated with atherosclerosis and coronary heart disease. Recent evidence suggests that it is the total number of circulating LDL-C particles of various sizes that most closely predicts atherosclerosis risk. This review focuses on the growing body of literature suggesting that niacin favorably alters the number of circulating LDL particles of various sizes. Niacin Overview It was initially reported in 1955 that nicotinic acid (niacin) lowered cholesterol levels in normal subjects as well as in patients with hypercholesterolemia. [1] There have been many subsequent studies that have supported niacin as a broad-spectrum lipid-regulating medication. [2] Niacin reduces total cholesterol, triglycerides, VLDL-C, LDL-C and lipoprotein (a) (Lp[a]) levels, in addition to increasing HDL-C levels. [3] In its present clinical use, niacin is available in a number of formulations. Extended-release niacin (ERN) is the most widely used prescription niacin and has a better side-effect profile than the other available preparations, including dietary supplement versions of niacin. Dietary supplement niacin comes in many forms, including immediate-release or crystalline, sustained- or time-released and no-flush or flush-free formulations. Immediate-release niacin is effective and safe, even at relatively high doses (up to 12 g/day), but it has the highest incidence of flushing. Sustained-release niacin causes flushing less frequently, but it is associated with increased hepatotoxicity. Flush-free niacin is safe and well tolerated, but it has low efficacy because of limited bioavailability. [4] In an analysis of the US FDA adverse event reporting (AER) database, Alsheikh-Ali et al. described that the rate of serious AERs associated with dietary supplement formulations of niacin was 6.2-fold higher and the rate of liver toxicity was 6.7-fold higher when compared with ERN. [5] Of note, in this database, there