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.