riboflavin

Riboflavin, also known as vitamin B2, is a water-soluble vitamin essential for human health. It acts as a precursor to the coenzymes flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), which participate in numerous redox reactions throughout energy metabolism.

In the body, FMN and FAD are required for the oxidation–reduction steps involved in the metabolism of carbohydrates, fats, and proteins. They also support other cellular processes, including the functioning of the antioxidant system via glutathione reductase. Riboflavin is not stored in large amounts, so a regular dietary supply is needed.

Dietary sources of riboflavin include dairy products, eggs, lean meats, fortified cereals, and green vegetables. It is relatively stable to heat but is sensitive to light, so storage in opaque containers helps preserve content.

Deficiency is uncommon in developed countries but can occur with poor intake, malabsorption, or certain illnesses and medications. Ariboflavinosis, the deficiency syndrome, presents with sore throat, redness and inflammation of the mouth and tongue (stomatitis, glossitis), cheilosis (cracks at the corners of the mouth), seborrheic dermatitis, and, in severe cases, anemia or corneal vascularization.

Recommended daily allowances for adults are about 1.3 mg/day for men and 1.1 mg/day for women, with higher needs during pregnancy and lactation. Riboflavin has a low toxicity risk; no upper intake level is established, and excess amounts are excreted in urine. High-dose supplements may color urine bright yellow.