Niacin
What is the importance of niacin?
Niacin or nicotinic acid belongs to B-complex group of vitamins and is essential vitamin for maintaining optimal health. Niacin is required for metabolism of the major constituents of food namely proteins, fats and carbohydrates. Niacin is also essential for smooth functioning of nervous system, GIT (gastrointestinal system) and also for maintaining normal texture of skin or maintaining skin health.
In which way niacin differs from other B-complex group of vitamins?
Niacin differs from other B-complex group of vitamins in that it is produced from an essential amino acid “tryptophan” which serves as a precursor of niacin (in other words a single chemical step of tryptophan produces niacin). Another way niacin differ from other B-complex group of vitamins is that niacin is not excreted in the urine as such (as niacin), unlike other B-complex group of vitamins which are excreted in urine without undergoing any change. Niacin is excreted in the urine as in two of its major metabolites namely N-methyl-nicotinamide and N-methyl-pyridone.
What are the food sources of niacin?
As mentioned earlier, niacin is produced from essential amino acid tryptophan, so any food source which is rich in tryptophan is a good source of niacin. Food sources which are rich in niacin are liver, meat, kidney, fish, poultry, and legumes, peanuts etc. many of the foods are poor in niacin but are rich in tryptophan and can act as good source of niacin e.g. milk, as milk proteins are rich in niacin. Many cereals and grains (e.g. maize) have niacin in “bound form” and niacin is not available for use and can not act as source despite having good quantity of niacin in bound form.
Niacin is formed from tryptophan with just single chemical step. To produce 1 mg of niacin, approximately 60 mgs of tryptophan is required.