Niacin is one of eight B vitamins and is part of two co-enzymes (abbreviated as NAD and NADP). Within both co-enzymes, niacin has a role in many biological functions within the body. NAD helps convert carbohydrates, protein, fat and alcohol into energy and NADP is necessary for the synthesis of fatty acids. In addition to its function as a component of coenzymes, niacin has important roles in:

  • Digestion
  • Skin health
  • Nervous system functioning



In addition to the aforementioned responsibilities of this multifunctional vitamin, niacin, along with the other B vitamins, is crucial for energy support. All B vitamins have important functions in the energy-producing pathways that help the body make and use energy from food.

And, though deficiencies of most B vitamins are rare in the U.S., an active person’s need for B vitamins may increase with exercise since physical activity stresses metabolic pathways. Despite this potential need for more niacin, dietary intake data shows many athletes, particularly women, do not consume adequate amounts of B vitamins from food. Men often fair better because they consume more food which increases the likelihood that they will consume more nutrients as well.


Deficiency and Excess

A severe deficiency in niacin, called pellagra, may result from inadequate consumption of either niacin or the amino acid tryptophan, which can also make NAD. In addition, a deficiency of other micronutrients necessary for converting tryptophan to niacin may also result in the appearance of pellagra.

While this disease is almost nonexistent in the U.S. and other industrialized countries, chronic alcoholics and people who have impaired tryptophan pathways in the body have a higher risk of developing pellagra.

Symptoms include: a symmetrical pigmented red rash on skin that has been exposed to sunlight, diarrhea, delusions, bright red tongue, mental confusion and scaly skin sores.


“Niacin Flush”

Excess niacin intake will typically first result in flushed, red appearance on the face, arms and chest and headaches. In addition, a person may experience digestive discomfort, and in very large doses such as those used to treat high cholesterol (3 to 9 grams per day), patients may experience increased blood sugar and liver damage.



Several foods contain niacin including:

  • lean meats
  • fish
  • poultry
  • dairy products
  • nuts
  • eggs
  • legumes
  • enriched grains and grain products (like cereals, breads and pasta)


In addition to food and supplement sources of niacin, the amino acid tryptophan is converted into niacin in the body. Tryptophan can be found in several foods including cheese, chicken, eggs, fish, milk, nuts, peanut butter, peanuts, pumpkin seeds, sesame seeds, soy, tofu and turkey.


Niacin. Medline Plus. NIH. Retrieved from: February 26, 2013.

Niacin and Niacinamide (Vitamin B3). Medline Plus, NIH. Retrieved from: February 26, 2013.

Tryptophan. Medline Plus. NIH. Retrieved from: February 26, 2013.

Pellagra. Medline Plus. Retrieved from: NIH. February 26, 2013.

Niacin. In: Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline (1998). National Academy of Sciences. Institute of Medicine. Food and Nutrition Board. Retrieved from: February 26, 2013.

AIM-HIGH Investigators, Boden WE, Probstfield JL, Anderson T, Chaitman BR, Desvignes-Nickens P, Koprowicz K, McBride R, Teo K, Weintraub W. Niacin in patients with low HDL cholesterol levels receiving intensive statin therapy. New Engl J Med 2011;365(24):2255-67. Retrieved from: February 26, 2013.

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