Biotin, a B vitamin, is an essential nutrient that is naturally present in some foods. This water-soluble vitamin is a cofactor for five carboxylases (propionyl-CoA carboxylase, pyruvate carboxylase, methylcrotonyl-CoA carboxylase [MCC], acetyl-CoA carboxylase 1, and acetyl-CoA carboxylase 2) that catalyze critical steps in the metabolism of fatty acids, glucose, and amino acids . Biotin also plays key roles in histone modifications, gene regulation (by modifying the activity of transcription factors), and cell signaling.
A UL has not been established for Biotin (Vitamin B7), because a toxic level has not been observed from food sources or from longer-term intakes of high-dose supplements.