Answer:
niacin or nicotinic acid one among the B-complex vitamins.
also called pellagra preventive factor of Goldberg.
source:
the natural sources include yeast, whole grains, cereals, pulsesl like beans, peanuts. milk, fish, eggs and vegetables are moderate sources.
the essential amino acid tryptophan can serve as a precursor for the nicotinamide coenzymes.(conversion ratio 60:1)