Flavin adenine dinucleotide (FAD) is a vital coenzyme derived from riboflavin (vitamin B2) and is crucial in various metabolic processes. FAD is involved in the metabolism of fats, proteins, and carbohydrates, helping to convert nutrients from the diet into usable energy. As a critical component in cellular respiration, FAD is a carrier of electrons during redox reactions in the mitochondria. During these reactions, FAD alternates between oxidized (FAD) and reduced (FADH2). In its reduced form, FADH2 delivers electrons to the electron transport chain, a series of reactions that generate adenosine triphosphate (ATP). Beyond its role in energy production, FAD is essential in antioxidant defense mechanisms and certain detoxification processes. Its importance in biological processes underscores the necessity of adequate vitamin B2/riboflavin intake for maintaining cellular health and metabolic efficiency.