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Vitamin B3

Vitamin B3

Alternate Names

  • niacin
  • nicotinic acid
  • nicotinamide


Niacin (vitamin B3) is a water-soluble vitamin. It is one of the eight B complex vitamins. These include vitamins B1, B2, B6, B12, folate, biotin, and pantothenic acid. Water-soluble vitamins are not stored in the body.

What food source is the nutrient found in?

Good sources of niacin include:
  • enriched and fortified grain products
  • legumes like peas and beans
  • meats, especially organ meats, like liver
  • poultry
  • fish
  • peanut butter
Niacin can be made in the body from the amino acid known as tryptophan. Another B vitamin, Vitamin B6, is needed to convert niacin to tryptophan. Amino acids are the building blocks of proteins. So, protein-rich foods can be good sources of niacin. Examples of these foods are:
  • 3 oz turkey = 4.5 mg of niacin
  • peanut butter 2 Tbsp. = 4 mg of niacin
  • 3 oz tuna = 11.8 mg of niacin
  • 1 cup wheat flour = 7.4 mg of niacin
  • 1 cup cheerios = 5.0 mg of niacin

How does the nutrient affect the body?

Niacin works closely with vitamin B1, B2, B6, pantothenic acid, and biotin to break the carbohydrates, fats, and proteins in food down into energy. Without niacin, the body would not be able to convert the food we eat into energy. Niacin also helps enzymes function in the body. Enzymes are used by the body in many reactions. Niacin helps keep the skin, digestive tract, and nerves healthy.


In the early 1900's, a disease called pellagra was common in the southern United States. At this time, corn was a staple of the diet. This diet provided neither niacin-rich foods like meats and certain vegetables, nor protein-rich foods containing tryptophan. Pellagra was caused by this lack of niacin intake. Pellagra is uncommon today. This is due to widespread niacin enrichment of most cereals, flours, pastas, and corn meals.
For people who eat enough protein, niacin deficiency is not common. Niacin deficiency symptoms include:
  • weakness
  • loss of appetite
  • digestive upsets
  • insomnia
  • headaches
  • irritability
  • frequently, a sore, swollen, purple-red tongue.
More drastic niacin shortfall leads to pellagra, which can result in symptoms such as:
  • skin and gastrointestinal lesions
  • swollen mucous membranes
  • diarrhea
  • dementia
  • death, in extreme cases
But, as mentioned above, pellagra is all but a thing of the past in the United States.
In recent years, niacin has been used with some success to treat people with high cholesterol levels. The high dose required to bring about any change in cholesterol, up to 3,000 mg per day, can bring on side effects. Common side effects include flushing of the skin and itching. High doses of niacin may also cause liver damage or stomach ulcers. Because of these potentially dangerous side effects, niacin should only be used to control cholesterol when prescribed by a doctor.
The Recommended Dietary Allowance, called the RDA, for niacin is:
  • Adult males, age 19 to 50: 19 milligrams (mg)
  • Adult males, age 50 and older: 15 mg
  • Adult females, age 19 to 50: 15 mg
  • Adult females, age 50 and older: 13 mg
  • Pregnant women: 17 mg
  • Lactating or breastfeeding women: 20 mg


Mahan, K, MS, RD, CDE&Escott-Stump, S., MA, RD, LDN. (2000). Krause's Food, Nutrition,&Diet Therapy (10th ed.). Pennsylvania: W.B. Saunders Company.

Somer, E., MA, RD.&Health Media of America. (1995). The Essential Guide To Vitamins and Minerals (2nd ed.). New York: HarperCollins Publishers, Inc.

Duyff, R., MS, RD, CFCS. (1996). The American Dietetic Association's Complete Food&Nutrition Guide. Minnesota: Chronimed Publishing.

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