Vitamin B2

Riboflavin (B2) is an essential water-soluble vitamin absorbed in the small intestine. It is converted to flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN), which are critical cofactors for many oxidoreductase enzymes including succinate dehydrogenase, acyl-CoA dehydrogenase, and cytochrome P450 reactions. Deficiency is rare but can occur with malabsorption, alcoholism, or inadequate diet, particularly in the context of anorexia nervosa or extreme poverty. Ariboflavinosis (B2 deficiency) presents with angular cheilitis (cracks at the corners of the mouth), glossitis (inflamed tongue), seborrheic dermatitis, and occasionally photophobia and ocular problems. These manifestations are part of Plummer-Vinson syndrome when combined with iron deficiency. Diagnosis is based on clinical presentation and low urinary riboflavin. Treatment is riboflavin supplementation (10-20 mg/day). RDA is 1.3 mg/day for adult males and 1.1 mg/day for adult females. Food sources include eggs, dairy, almonds, and mushrooms.