Niacin: A Vital B Vitamin for Health and Metabolism

Niacin, or vitamin B3, is a water-soluble B vitamin crucial for DNA repair and energy metabolism. Known chemically as either nicotinic acid or nicotinamide, niacin was first produced from nicotine in tobacco in 1867. However, in the early 1940s, once its importance as a vitamin was established, it was renamed “niacin” to prevent any confusion with nicotine.

Niacin’s role in the body is extensive, primarily because it forms part of essential coenzymes like NAD (nicotinamide adenine dinucleotide) and NADP (nicotinamide adenine dinucleotide phosphate). These coenzymes participate in over 200 metabolic pathways, including the production and breakdown of carbohydrates, fatty acids, and amino acids. Niacin is also involved in vasodilation, or blood vessel widening, which supports blood flow and may help reduce blood pressure. A deficiency in niacin can lead to pellagra, a disease characterized by diarrhea, dermatitis, dementia, and, if untreated, can be fatal.

Historically, pellagra was linked to corn-based diets, especially after the introduction of maize to Europe in the 1770s. Corn lacks bioavailable niacin, which led to widespread cases of pellagra until the link was confirmed in 1937 by American scientist Joseph Goldberger. Although pellagra is rare in industrialized countries today, cases may still occur, particularly in alcoholics, where it can manifest mainly as encephalopathy, a brain disorder.

Niacin is not only obtained from dietary sources but can also be synthesized by the body from the amino acid tryptophan, with the help of vitamin B2 (riboflavin). The Recommended Dietary Allowance (RDA) for adults ranges from 13 to 20 mg per day, with increased requirements in pregnancy, lactation, and periods of active physical work. Children need between 5 to 16 mg daily. Dietary sources include meats, poultry, fish, nuts, peanuts, and enriched or whole grain products.

In grains, niacin exists in a bound form known as niacytin, attached to small peptides and carbohydrates, making it less bioavailable. Nonetheless, with the widespread availability of niacin-rich foods, severe deficiencies have become rare, underscoring the success of fortification and dietary awareness in maintaining adequate niacin levels for health.
Niacin: A Vital B Vitamin for Health and Metabolism

Food sources of niacin (vitamin B3)

Niacin (nicotinic acid) is one of vitamin B. This compound is part of an enzyme system regulating reduction reactions in the body.

It is also a compound that dilates blood vessels. Deficiency of niacin causes pellagra (a disease that causes diarrhea, dermatitis, nervous disorders, and sometimes death).

In general, niacin is widespread in foodstuff. Cereals seeds, meat and fish are good food sources of niacin, which converts trigonelline.

All foods containing complete protein, such as the above mentioned, and also milk and eggs, are good source of the precursor of niacin, tryptophan. Tryptophan an amino acid present in some of these foods, can be converted to niacin in the body.

Lean meat, poultry, and peanuts are good sources of both niacin and tryptophan, as are beans, peas, other legumes, most nuts, and several whole grain or enriched cereal products.

The niacin vitamers in foods include nicotinic and nicotinamide, which occur in limited quantities in the free form, and their coenzymes, nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate.
Food sources of niacin (vitamin B3)