Monday, November 29, 2021

Niacin (Vitamin B3)

Niacin is a water-soluble B vitamin important for DNA repair and energy metabolism. Also known as vitamin B3. Niacin is the generic term for nicotinic acid (pyridine 3-carboxylic acid) and nicotinamide (nicotinic acid amide) and the coenzyme forms of the vitamin.

In 1867, nicotinic acid was produced from nicotine in tobacco. In the early 1940s, with its role as a vitamin established, it was renamed “niacin” so people wouldn’t confuse it with nicotine.

Nicotinic acid and nicotinamide are colorless crystalline substances; each is insoluble or only sparingly soluble in organic solvents.

Nicotinamide is the active form, which functions as a constituent of two coenzymes, namely, nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP).

Niacin is part of coenzyme that participates in the production and breakdown of carbohydrates, fatty acids, and amino acids. It involved in at least 200 metabolic pathways. It is also a compound that dilates blood vessel.

A sufficient intake of vitamin B3 (niacin) is important as it helps the body to
• convert food into glucose, used to produce energy
• produce macromolecules, including fatty acids and cholesterol
• DNA repair and stress responses.

Clinical evidence of niacin deficiency includes fatigue, poor appetite, diarrhea, irritability, headache, emotional instability and possible memory loss. These may lead to changes in the skin, mucosa of the mouth, stomach and intestinal tract and the nervous system. These changes are called “pellagra”, which means “raw skin”.

Pellagra is characteristically associated with maize based diets. The disease pellagra has been known since the introduction of corn to Europe in the 1770s. The connection between pellagra and niacin was confirm in 1937 by an American scientist who reaching for the cause of pellagra.

In industrialized country, particularly among alcoholics, niacin deficiency may present with only encephalopathy.

Niacin comes from the diet, but the body can also manufacture it from the amino acid tryptophan, with riboflavin helping out in the process.

Adults require 13-20 mg niacin. In pregnancy, lactation and active muscular work, niacin requirement is further increased by 3-4 mg. Children require 5-16 mg niacin.

Yeast, liver, poultry, lean meats, nuts and legumes contribute most of the niacin obtained from food. In cereal products (e.g., corn, wheat), niacin is bound to certain components of the cereal and is thus not bioavailable.

The amino acid tryptophan contributes as much as two thirds of the niacin activity required by adults in typical diets. Important food sources of tryptophan are meat, milk and eggs.
Niacin (Vitamin B3)

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