Niacin, also known as vitamin B3, is a water-soluble vitamin. Water-soluble vitamins are stored in the body in very limited amounts and are excreted through the urine. Therefore, it is a good idea to have them in your daily diet. In addition to getting niacin from dietary sources, the body can synthesize a form of niacin from the amino acid tryptophan.
Niacin’s functions include:
A niacin deficiency is called pellagra. The most common symptoms affect the skin, the digestive system, and the nervous system. Symptoms of niacin deficiency include:
For adults, the tolerable upper intake level (UL) for niacin from dietary sources and supplements combined is 35 mg. Niacin toxicity does not seem to occur when its only source is foods which have not been fortified with niacin. Symptoms of niacin toxicity have been reported in people using niacin supplements.
Symptoms of toxicity include:
Major Food Sources
Populations at Risk for Niacin Deficiency
The following populations may be at risk for niacin deficiency or have an increased need for niacin and may require a supplement:
Several well-designed clinical studies have shown that niacin can lower LDL-cholesterol and triglycerides (high blood levels of LDL-cholesterol and triglycerides are considered unhealthy); studies have also shown that niacin can raise HDL-cholesterol (higher blood levels of HDL-cholesterol are considered healthy). However, the studies that found positive results used pharmacologic doses of niacin. These doses are much larger than the current recommended dietary allowances (RDA) and should only be used under the supervision of a qualified healthcare provider.
Tips For Increasing Your Niacin Intake:
To help increase your intake of niacin:
American Dietetic Association
Dietitians of Canada
Advanced Nutrition and Human Metabolism. West Publishing Company; 2000.
Vitamin B3 (niacin). University of Maryland Medical Center website. Available at: http://www.umm.edu/altmed/articles/vitamin-b3-000335.htm. Accessed July 17, 2012.
Niacin. Oregon State University Linus Pauling Institute's Micronutrient Information Center website. Available at: http://lpi.oregonstate.edu/infocenter/vitamins/niacin/. Updated June 2007. Accessed July 17, 2012.
The Nutrition Desk Reference. Keats Publishing; 1995.
Last reviewed July 2012 by Brian Randall, MD