• by: Fondazione Valter Longo
  • April 11th, 2022

Vitamin PP (or B3), called niacin, is part of the group of water-soluble vitamins, i.e., those vitamins that dissolve in water and which, not being accumulated by the human body, must be taken every day through food. Niacin is essential for a series of biological reactions in the body.


Composed of two molecules, nicotinic acid and nicotinamide (in plants, the first, and in animal tissues, the second), vitamin PP is important for many physiological processes. It participates in cellular respiration, as a coenzyme in the respiratory chain, and in the production of energy.

Vitamin PP is also useful for the metabolism of carbohydrates, proteins, and fats. It is involved in amino acid synthesis too. On a cardiovascular level, then, niacin promotes blood circulation and reduces cholesterol levels. In addition, it is good for the skin and preserves the health of the gastric mucous membranes and intestines.

Finally, vitamin PP is also essential for the proper functioning of the nervous system, and it is useful in case of stress and anxiety, as well as improving memory and sleep. Niacin also has a tonic effect in counteracting feelings of weakness and fatigue, both physical and mental.



The recommended daily intake is 6.6 mg for every 1,000 kilocalories taken with food, in other words, 18 mg per day for an adult man, 14 mg for women, which rises to 22 mg during pregnancy and breastfeeding. In children, it ranges from 7 mg during childhood up to 18 mg during adolescence.

In Italy in the early 1900s, its deficiency was associated with pellagra, a disease that causes dry and flaky skin with red spots, intestinal disorders, gastro-intestinal lesions, diarrhea, neurological dysfunctions, and schizophrenia. This disease was widespread among the poor population who ate mainly corn (as well as almost no animal food). In fact, corn, in addition to being low in niacin, is rich in a substance (anti-vitamin PP) that combines with PP and makes it unavailable.

Nowadays, a niacin deficiency can cause various symptoms: headache, irritability, muscle wasting, weight loss, irregular bowel, difficult digestion, nausea, vomiting, bad breath, dermatitis, and gum and tongue problems (glossitis). Even an overdose (due to the use of supplements) can cause side effects such as flushing, low blood pressure, itching, erythema, headache, pain in the upper abdomen, nausea, and diarrhea.

A balanced and varied diet, with a sufficient intake of food of animal origin, guarantees an adequate intake of vitamin PP. In the event of a deficiency, a doctor or nutritionist can recommend the intake of vitamin PP supplements for older adults, those who practice sports at a medium-high level, those who carry out heavy physical activities, as well as to those who have suffered burns to promote cell regeneration.


Niacin is synthesized by the body from tryptophan, an essential amino acid found in animal proteins. For this reason, the main sources of vitamin PP are foods of animal origin (in the form of nicotinamide), especially white meats (turkey and veal), red meat, and beef liver. In fish, niacin is mostly in tuna, salmon, anchovies, sardines, and swordfish. Milk and cheese are also rich in this vitamin, while eggs contain a low quantity.

Among foods of plant origin, vitamin PP (as nicotinic acid) is abundant in whole grains, dried legumes, and peanuts, while fruits and vegetables in general contain little. Niacin is also present in brewer’s yeast. In grains, niacin is bound to peptides, glycopeptides, or polysaccharides. In corn it becomes available only if treated in a basic environment: for this reason, the niacin of Mexican tortillas (which use treated cornmeal) is absorbable by the body, while that of the Italian classic polenta is not. Niacin is also contained in coffee as a transformable methylated derivative. During the roasting process of the beans, it is transformed into bioavailable nicotinic acid for our body.


Vitamin PP has a stable structure at different temperatures. However, cooking can still induce a loss due to its great solubility in water. It is therefore recommended to stew vegetables rich in this vitamin in a pan without water or to steam them.


  • Vitamine – Informazioni generali – EPICENTRO (last viewed 02/07/2022)

  • Vitamine – Studi – EPICENTRO (last viewed 02/07/2022)

  • LARN – Livelli di assunzione di riferimento per la popolazione italiana: VITAMINE. Fabbisogno medio (AR); valori su base giornaliera – Società Italiana di Nutrizione Umana-SINU, 2014 (last viewed 02/07/2022)

  • Vitamin and Mineral Supplement Fact Sheets – NIH National Institute of Health (last viewed 02/07/2022)

  • Niacin – NIH National Institute of Health (last viewed 02/07/2022)



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