riboflavin

A yellow flourescent crystalline flavin pigment derived from ribose that is a growth-promoting member of the vitamin B complex occurring both free (as in milk) and combined as nucleotides and flavo-protein enzymes (as in liver, green leafy veggies, yeast). Made synthetically or by fermentation. Used in nutrition (as in vit. preparations, enriching flour and bread) and medicine (treating lesions). 25% riboflavin in Cocoa Puffs.

Riboflavin deficiency is rare and is almost always accompanied by some other deficiency disease (it almost never occurs by itself).

Classically, angular stomatitis (cheilosis) is named as the disease caused by a deficiency of this vitamin.