Niacin (nicotinic acid) in large amounts has been used to decrease low-density lipoprotein (LDL) cholesterol and triglyceride levels and to increase high-density lipoprotein (HDL) cholesterol levels. Symptoms may include flushing and, rarely, hepatotoxicity.
Niacin derivatives include nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), which are coenzymes in oxidation-reduction reactions. They are vital in cell metabolism.
(See also Overview of Vitamins and table Sources, Functions, and Effects of Vitamins.)
Immediate- and sustained-release preparations of niacin (but not nicotinamide) may affect lipid levels. However, whether niacin reduces risk of coronary artery disease and stroke is unclear (1).
1):
Triglyceride levels decrease 15 to 20%.
HDL cholesterol levels increase 15 to 30%.
LDL cholesterol levels decrease < 10%.
Lipoprotein(a) levels decrease approximately 20%.
niacin has the potential to cause complications among people with a liver disorder.
Flushing, which is prostaglandin-mediated, is more common with immediate-release preparations. It may be more intense after alcohol ingestion, aerobic activity, sun exposure, and consumption of spicy foods. Flushing is minimized if niacinniacin
Hepatotoxicity may be more common with some sustained-release preparations. Some authorities recommend checking levels of uric acid, blood glucose, and plasma aminotransferases every 6 to 8 weeks until the dose of niacin has been stabilized.
Reference
1. AIM-HIGH Investigators, Boden WE, Probstfield JL, et al. Niacin in patients with low HDL cholesterol levels receiving intensive statin therapy [published correction appears in N Engl J Med. 2012 Jul 12;367(2):189]. N Engl J Med. 2011;365(24):2255-2267. doi:10.1056/NEJMoa1107579
