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Niacin (Vitamin B3)
Chemical Structures
Food Sources
Niacin in the Body

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Niacin Crystals
Niacin Crystals
Copied without permission from Roche Product Information


Niacin (nicotinic acid and the amide derivative nicotinamide) is one of the water soluble B-vitamins. In the blood, brain, kidney and liver it is converted to the coenzymes nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), both of which are involved in the generation of energy in cells. Tryptophan is an amino acid which is a provitamin of niacin.


Chemical Structures

The chemical structure of Nicotinic Acid

Fig.1 The Chemical Structure of Nicotinic Acid
3D Structure of Nicotinic Acid

The Chemical Structure of Nicotinamide

Fig.2 The Chemical Structure of Nicotinamide

The chemical structure of Tryptophan

Fig.3 The Chemical Structure of Tryptophan


Principal Sources in Food

Both forms of niacin are widely occurring in nature. Nicotinic acid is the predominant form in plants and nicotinamide in animals. The major dietary sources of niacin are:
  • Yeast extract
  • Liver
  • Meats
  • Oily fish
  • Nuts
  • Legumes
Other sources include:
  • Green leafy vegetables
  • Milk and milk products
Important dietary sources of tryptophan are:
  • Meat
  • Milk
  • Eggs

Niacin in the Body

Deficiency of niacin results in a disease called Pellagra, the symptoms of which include:
  • Dermatosis
  • Dementia
  • Diarrhoea
  • Nervous disorders which can lead to paralysis of the extremities

Did You Know? An earlier name for niacin was PP factor (pellagra-preventative factor).



Nicotinic acid and nicotinamide are both stable to light, heat, air and alkali.



Niacin can be synthesised by the oxidation of 5-ethyl-2-methylpyridine. A method for producing nicotinamide via 3-methylpyridine uses the starting products acrolein and ammonia.


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