Vitamin B3 (PP, niacin)
To be precise, in this case it would be more correct to talk not about vitamin, but a group or family of the vitamin PP, which is composed of two chemically and biologically related compounds: nicotinic acid and its amide (nicotinamide). In the body, they are easily converted into one another and thus have the same vitamin activity.
History of discovery
Nicotinic acid has long been known: in 1866 it was isolated by the German chemist Hubert, through the oxidation of nicotine extracted from tobacco. But up until the 1940s, no one ever suspected that nicotinic acid has vitamin activity. It was recognized as a vitamin after it turned out that it perfectly cures pellagra - a serious illness suffered by thousands of people who ate mainly corn.
This explains the name "vitamin PP" - from the initial letters of the two Latin words «preventive pellagra».
Pellagra was widespread in Egypt, Italy, Romania, Bulgaria. In 1881 in Italy there were more than 100,000 cases of pellagra; in Egypt in 1915, more than 400 000 people suffered from it. Mass epidemic of pellagra took place in the early decades of the XX century in southern states of the US.
The clinical picture of pellagra is characterized by three main manifestations, designated as three "D": diarrhea - the gastrointestinal tract disorder; dermatitis - skin lesions (hence the name of the disease: rella agra - flaky skin in Italian) and dementia - a mental disorder with loss of memory, dementia and delirium.
Pellagra was being caused, as mentioned above, mainly with a preferential consumption of maize, in which nicotinic acid is chemically bonded to form which cannot be absorbed by man. Furthermore, maize protein is poor with tryptophan, thus this source of vitamin PP is ineffective for people, who mainly feed on corn.
What does vitamin PP do?
Along with vitamins B1 and B2, takes part in the energy metabolism. It attaches itself to the proteins and creates hundreds of different enzymes, which turn carbohydrates, fats and proteins reserves in living cells into energy.
Vitamin PP, niacin or nicotinic acid, improves carbohydrate metabolism, has a vasodilatory effect, helps to heal of wounds. This vitamin has a lipid-lowering activity: it causes a decrease of cholesterol, low density atherogenic lipoproteins, and especially triglycerides.
The amino acid tryptophan, which operates in the enzymes which involved in more than 50 metabolic reactions, converts into niacin. Vitamin B6 is a cofactor in this reaction.
Where can vitamin PP be found?
Unlike most other vitamins, which can only be found in of food, vitamin PP synthesize in human body from essential amino acid called tryptophan. However, this does synthesis is not sufficient to fully cover our need for vitamin PP.
The best sources of vitamin PP are brewer's yeast, liver and kidney of cattle, wheat bran, bread from wheat flour or whole grain, some mushrooms.
How much vitamin PP do you need?
The human body requires 14 to 28 mg of vitamin PP daily.
Lack and excess of vitamin PP.
The disease caused by the lack of niacin is called pellagra and is characterized by dermatitis, diarrhea and dementia (breach of brainwork). The initial symptoms of lack of niacin are insomnia, anxiety, irritability, difficulty concentrating, and so on. An excess of vitamin PP is rare, but can cause liver malfunctions.
