Niacin, a B vitamin Overview of Vitamins Vitamins are a vital part of a healthy diet. The recommended dietary allowance (RDA)—the amount most healthy people need each day to remain healthy—has been determined for most vitamins. A safe... read more , is essential for the processing (metabolism) of carbohydrates, fats, and many other substances in the body and for the normal functioning of cells. Good sources of niacin include dried yeast, liver, red meat, poultry, fish, legumes, and whole-grain or enriched cereal products and bread.
The term "niacin" is used in two ways: as a synonym for nicotinic acid and as a broader term that includes nicotinamide and nicotinic acid, two forms of this B vitamin.
High doses of nicotinic acid can have the following beneficial effects:
Increase high-density lipoprotein (HDL—the good) cholesterol Overview of Cholesterol and Lipid Disorders The body needs fats for growth and energy. It also uses them to synthesize hormones and other substances needed for the body’s activities. The body may deposit excess fat in blood vessels and... read more levels
Moderately decrease low-density lipoprotein (LDL—the bad) cholesterol levels
However, whether taking nicotinic acid supplements reduces the risk of coronary artery disease Overview of Coronary Artery Disease (CAD) Coronary artery disease is a condition in which the blood supply to the heart muscle is partially or completely blocked. The heart muscle needs a constant supply of oxygen-rich blood. The coronary... read more and stroke Overview of Stroke A stroke occurs when an artery to the brain becomes blocked or ruptures, resulting in death of an area of brain tissue due to loss of its blood supply (cerebral infarction) and symptoms that... read more is unclear.
Such high doses of nicotinic acid can cause flushing, itching, gout Gout Gout is a disorder in which deposits of uric acid crystals accumulate in the joints because of high blood levels of uric acid (hyperuricemia). The accumulations of crystals cause flares (attacks)... read more , and liver damage (rarely) and increase the level of sugar (glucose) in the blood. Flushing may be worse after drinking alcohol, being physically active, being in the sun, and eating spicy foods.
Most side effects can be minimized by starting with a relatively low dose and gradually increasing the dose. Taking aspirin before taking nicotinic acid and taking nicotinic acid after meals also help.
If the side effects of nicotinic acid are intolerable, the dose may be decreased, other (especially extended-release) formulations may be tried, or nicotinic acid may be stopped and another lipid-lowering drug Lipid-Lowering Drugs substituted.