Niacin is an important type of B vitamin found in animal foods like red meat, liver and fish. Although humans can make it from the amino acid tryptophan, this synthesis is inefficient; thus niacin is still considered a vitamin (an organic substance that must be ingested). It is often referred to as vitamin B3 because it was the third of the discovered vitamins of B group.

The discovery of the role of niacin is closely linked with the story of pellagra. This disease was widespread throughout human history, especially among impoverished people whose diet consisted almost entirely of corn products. Symptoms of pellagra include diarrhea, inflamed mucous membranes, mental confusion, delusions and scaly skin sores.

History of pellagra

Pellagra was unknown to the physicians of the ancient world and the Middle Ages. It was initially described by the physician Gaspar Casal in Spain in 1735, soon after the maize was introduced into Europe. The name of the disease was established in 1771 by an Italian physician Francesco Frapolli.

Due to the great increase in the use of maize in northern part of Italy, pellagra became so widespread that a special hospital (known as Legano) was built in 1784, exclusively for pellagra patients. Reports on the occurrence of pellagra appeared soon thereafter in France (1829), Romania (1858) and Egypt (1874).

After 1900 pellagra became a significant health problem in the United States as well, particularly in the South. It closely followed the introduction of a new grain processing method that removed most of the vitamins from processed grain. There was a specific shift from the usage of coarsely ground corn meal in local, water-driven mills to finely bolted meal by large milling companies.

The outbreaks of pellagra were so ubiquitous and severe that a majority of physicians considered the cause to be an infectious agent. The true nature of disease was determined when the Federal Government of the United States sent a doctor from New York, Joseph Goldberger, to study the disease.

The discovery of niacin

Nicotinic acid was synthesized in 1867 by oxidation of nicotine and widely used in photography. It was long thought that it has nothing to do with food or health issues, until German scientists demonstrated that nicotinic acid occurs in yeast and in rice polishing. There it was isolated by the Polish-American biochemist Casimir Funk in 1912, while he was trying to find a cure for another disease known as beriberi (nutritional disorder caused by a deficiency of thiamine).

Since nicotinic acid had no effect on beriberi, he abandoned his work with that compound. But although he was wrong, he showed that this nicotinic acid probably had some nutritional value. It was left to the Austrian-American physician Joseph Goldeberger to find the connection between nicotinic acid and deficiency diseases it can cause.

In 1915, Goldberger conducted a series of experiments on 11 healthy volunteer prisoners in a Mississippi jail and found that he could induce pellagra by altering their diets. He concluded that the disease was caused by the absence of some factor that was lacking in corn, but that could be found in meat and milk. He named it the P-P (for pellagra-preventative) factor.

The chemical structure of that factor was subsequently discovered in 1937 by the American biochemist Conrad Arnold Elvehjem. He induced a black tongue in dogs by feeding them the Goldberger diet, and then cured the disease by supplementing their diet with nicotinic acid. He also isolated the P-P factor from active liver extracts, showing that this factor is actually nicotinic acid (subsequently named niacin for nicotinic acid vitamin).

After this discovery, grain products (wheat, maize) were enriched with nicotinic acid or nicotinamide. Still, a wide scale social reform was needed to ensure proper implementation of such dietary modifications. The majority of sporadic cases in the developed countries are now seen in alcoholics, although in rare instances other patients can develop the disease as well (i.e. malabsorption or iatrogenic situations).