Vitamin B2
Vitamin B2 (riboflavin) is a water-soluble vitamin, part of the vitamin B complex, that is an important component of the cofactors flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN). The flavoproteins contribute to many cellular reactions, including the metabolism of several other vitamins.
Isolated deficiency of riboflavin is rare, it is usually seen in the context of a more generalized malnutrition. No toxicity of riboflavin excess has been described .
Interestingly, it was formerly known as vitamin G.