Riboflavin, also known as vitamin B2 is an easily absorbed colored micronutrient with a key role in maintaining health in humans and animals. It is the central component of the cofactors FAD and FMN, and is therefore required by all flavoproteins. As such, vitamin B2 is required for a wide variety of cellular processes. It plays a key role in energy metabolism, and for the metabolism of fats, ketone bodies, carbohydrates, and proteins.
Milk, cheese, leaf vegetables, liver, kidneys, legumes, yeast, mushrooms, and almonds are good sources of vitamin B2, but exposure to light destroys riboflavin.
The name "riboflavin" comes from "ribose" (the sugar whose reduced form, ribitol, forms part of its structure) and "flavin", the ring-moiety which imparts the yellow color to the oxidized molecule (from Latin flavus, "yellow"). The reduced form, which occurs in metabolism along with the oxidized form, is colorless.
Riboflavin is best known visually as the vitamin which imparts the orange color to solid B-vitamin preparations, the yellow color to vitamin supplement solutions, and the unusual fluorescent-yellow color to the urine of persons who supplement with high-dose B-complex preparations (no other vitamin imparts any color to urine).
Riboflavin can be used as a deliberate orange-red food color additive, and as such is designated in Europe as the E number E101.
Read more about Riboflavin: Discovery, Biochemical Function, Mechanism of Action As Cofactors and Flavoproteins, Riboflavin in Food: Occurrence, Sources and Stability, Toxicity, Industrial Synthesis